LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 


BIOLOGY 

LIBRARY 

G 


Class 


io 


Exposed  places  of  main  arteries. 


(  Seepages  314  an 


PHYSIOLOGY 


EXPEKIMENTAL  AND   DESOEIPTIYE 


BY 

BUEL  P.  COLTON,  A.M. 

AUTHOR  OF  "  PRACTICAL  ZOOLOGY,"  AND  PROFESSOR  OF  NATURAL  SCIENCE 
IN  THE  ILLINOIS  STATE  NORMAL  UNIVERSITY. 


"  What  a  piece  of  work  is  a  man  !  how  noble  in  reason  ! 
how  infinite  in  faculty  !  in  form  and  moving,  how  express 
and  admirable !  in  action,  how  like  an  angel !  in  appre- 
hension, how  like  a  god  !  the  beauty  of  the  world  !  the 
paragon  of  animals  ! " 


BOSTOX,  U.S.A. 

D.  C.  HEATH  &  GO.,  PUBLISHERS 
1910 


3IOLOGY 
!  BRARY 

G 


COLTON'S   PHYSIOLOGIES 


PHYSIOLOGY  :  Experimental  and  Descriptive  .        .        .    $1.12 
For  Normal   Schouls  and   Colleges.     440  pages.      Illus- 
trated in  colors. 

PHYSIOLOGY:   Briefer  Course 90 

For  High  Schools.     399  pages.     Illustrated  in  colors. 

PRACTICAL  PHYSIOLOGY 60 

Laboratory  Work  in  Physiology.     168  pages.     Illustrated. 

PHYSIOLOGY :  Practical  and  Descriptive         .        .        .       1.40 
This  consists  of  the  Briefer  Course  and  the  Practical  Physi- 
ology bound  in  one  volume. 

ELEMENTARY  PHYSIOLOGY   AND   HYGIENE     .        .         .60 

For  Grammar  Schools.     320  pages.     Illustrated. 

GOOD  HEALTH  FOR  GIRLS   AND  BOYS      ...         .45 

An  Introduction  to  the  Elementary  Physiology,  for  Inter- 
mediate Grades,  by  BERTHA  M.  BROWN.  164  pages. 
Illustrated. 


D.  C.  HEATH  &  CO.,  Publishers,  Boston,  New  York,  Chicago 


Ex.  and  Des. 


COPYRIGHT,  1898 
8v  BUEL  P.   COLTON. 


' 


PEE  FACE. 


WE  have  all  laughed  at  the  ridiculous  answers  given  to 
examination  questions  in  physiology.  But  such  absurd  state- 
ments ought  to  arouse  something  more  than  laughter.  They 
should  give  rise  to  serious  thought.  What  do  they  signify  ? 
That  children  make  gross  blunders  ?  But  they  do  not  make 
such  wild  statements  about  things  which  they  have  seen  and 
handled.  These  absurd  answers  are  a  sad  comment  on  the 
method  of  teaching.  They  point  not  to  stupidity  in  the  child, 
but  to  shortcoming  in  instruction. 

Many  years  ago  the  writer  became  convinced  of  the  utter 
futility  of  mere  book-work  in  teaching  physiology ;  he  sought 
all  available  means  of  making  the  subject  clear  and  full  of 
meaning  to  his  pupils.  These  illustrations,  experiments,  and 
dissections  have  multiplied  ;  in  the  hope  that  what  has  been  so 
useful  to  him  may  also  prove  helpful  to  others,  the  author 
presents  them  in  this  form  to  his  fellow-teachers. 

The  whole  of  the  manuscript  has  been  critically  read  by 
Dr.  G.  W.  Fitz  of  Harvard  University.  The  manuscript  has 
also  been  read  by  M.  F.  Arey,  State  Normal  School,  Cedar 
Falls,  Iowa ;  E.  R.  Boyer,  Hyde  Park  High  School,  Chicago, 
111. ;  H.  Garman,  State  Agricultural  College,  Lexington,  Ky. ; 
N.  A.  Harvey,  Normal  School,  West  Superior,  Wis. ;  W.  S. 
Jackman,  Chicago  Normal  School ;  A.  J.  McClatchie,  Throop 

iii 


212412 


iv  PREFACE. 

Polytechnic  Institute,  Pasadena,  Cal. ;  A.  1\  Ohlmacher,  Medi- 
cal Department,  University  of  Wooster,  Cleveland,  Ohio  j  and 
other  well-known  teachers  of  high  standing. 

The  manuscript  pertaining  to  the  eye  has  been  corrected 
by  the  well-known  oculist,  Dr.  Casey  A.  Wood  of  Chicago,  and 
that  on  the  ear  by  the  specialist,  Dr.  T.  Melville  Hardie. 

To  these  the  author  wishes  to  express  his  sincere  apprecia- 
tion of  their  valuable  assistance,  and  also  to  the  following,  who 
have  read  the  proof,  and  whose  criticisms  and  suggestions 
have  been  exceedingly  helpful :  A.  C.  Boyden,  Bridgewater, 
Mass. ;  Dr.  C.  F.  Hodge,  Clark  University,  Worcester,  Mass. ; 
Dr.  Frieda  E.  Lippert,  New  York  ;  Dr.  L.  B.  Wilson,  Uni- 
versity of  Minnesota,  Minneapolis,  Minn. ;  Dr.  Robert  H. 
Wolcott.  University  of  Nebraska,  Lincoln,  Neb. ;  W.  E. 
Wilson,  State  Normal,  School,  Providence,  E.I. ;  Dr.  Adolf 
Meyer,  Clark  University,  Worcester,  Mass.  ;  W.  H.  Chandler, 
State  Inspector  of  High  Schools,  Madison,  Wis. ;  Dr.  H.  B. 
Ward,  University  of  Nebraska,  Lincoln,  Neb.  ;  J.  E.  McGiJ- 
vrey,  Inspector  of  High  Schools  for  the  University  of  Illi- 
nois, Champaign,  111.  ;  George  B;  Aiton,  Inspector  of  High 
Schools  for  the  State  of  Minnesota,  Minneapolis,  Minn. ;  J. 
W.  Crabtree,  Inspector  of  High  Schools  for  the  University 
of  Nebraska,  Lincoln,  Neb. 

With  this  help  it  may  be  expected  that  the  book  will  be 
fairly  free  from  errors,  yet  for  such  as  may  be  found  the 
author  alone  is  responsible. 

The  author  acknowledges  his  dependence  on  the  larger 
standard  anatomies  and  physiologies,  especially  the  Practical 
Physiology  by  Foster  and  Langley,  the  Practical  Physiology 


PREFACE.  Y 

of  Stirling,  and  Wilder  and  Gage's  Anatomical  Technology ; 
many  hints  have  also  been  gathered  from  the  various  elemen- 
tary physiologies,  riot  only  in  the  subject-matter,  but  also  in 
the  illustrations. 

Thanks  are  due  the  following  publishers  for  permission 
to  make  extracts  from  their  books  on  the  subject  of  Alcohol : 
D.  Appleton  &  Co.,  P.  Blakiston,  Son  &  Co.,  F.  A.  Davis  Co., 
Henry  Holt  &  Co.,  J.  B.  'Lippincott  Co.,  Longmans,  Green  & 
Co.,  Macmillan  &  Co.,  and  W.  B.  Saunders.  Especial  thanks 
are  due  Mrs.  Mary  H.  Abel  for  permission  to  use  the  extended 
extracts  from  the  Lomb  Prize  Essay  on  Practical  Sanitary 
and  Economic  Cooking. 

All  of  the  illustrations,  with  four  exceptions,  have  been 
engraved  expressly  for  this  work.  In  all  cases  the  label  is 
placed  as  near  as  possible  to  the  thing  labeled.  The  author 
believes  most  strongly  in  this  style  of  labeling,  as  he  has 
learned  that  young  students  do  not  find  the  connection  be- 
tween the  letters  or  figures  of  the  ordinary  illustration  and 
the  explanation  below  (usually  in  fine  print).  Diagrams  have 
proved  very  useful,  since  many  of  the  anatomical  plates  pre- 
sent so  many  details  that  the  young  student  is  bewildered, 
and  does  not  seem  able  to  distinguish  between  the  important 
and  the  unimportant  features.  In  most  cases  the  dorsal  view 
is  presented,  so  that  the  right  and  left  of  the  organs  are  at 
the  right  and  left  of  the  reader.  The  ventral  view,  like  a 

mirror,  reverses  right  and  left. 

B.  P.  C. 
NORMAL,  ILL.,  December,  1897. 


TO    THE    TEACHER 


The  Equipment. — There  should  be  a  well-lighted  room, 
with  tables  two  feet  wide  and  four  and  a  half  feet  long,  for 
two  students  to  work  together.  The  tables  should  be  twenty- 
nine  inches  high,  and  provided  with  two  drawers. 

There  should  be  an  ample  supply  of  water,  soap,  and  towels, 
so  that  the  pupils  may  wash  their  hands  at  the  close  of  the 
work.  It  is  very  desirable  to  have  warm  water  after  dissect- 
ing, and  a  small  gasoline  stove  will  heat  water  enough  for 
several  large  classes.  If  there  is  no  convenient  sink,  a  long 
trough,  made  of  tin  or  galvanized  iron  and  stiffened  by  a  board 
casing,  will  serve  very  well. 

The  teacher  should  take  the  utmost  pains  to  have  every- 
thing connected  with  the  dissecting  work  as  neat  as  possible. 
Remove  all  superfluous  parts  and  scraps  as  soon  as  possible. 
Many  of  the  dissections  may  be  made  on  large  sheets  of  brown 
paper,  such  as  are  used  in  the  meat  market.  Each  student 
should  be  provided  with  a  dissecting  set,  which  ought  to  include 
at  least  a  scalpel,  scissors,  forceps,  and  blowpipe  ;  a  cartilage 
knife  is  also  desirable  for  the  rough  work,  to  save  the  edge  of 
the  scalpel.  A  more  convenient  form  of  blowpipe  is  made  by 
inserting  a  foot  of  rubber  tubing  between  the  mouthpiece  and 
the  tip,  as  this  is  easier  to  manage,  and  if  the  student  is  work- 
ing alone  he  can  see  what  he  is  doing.  A  set  of  anatomical 
models  is  almost  indispensable  for  good  work,  but  these  cannot 
take  the  place  of  dissection.  Such  models  can  be  obtained  of 

vii 


viii  TO   THE   TEACHER. 

almost  any  of  the  school-supply  firms  or  dealers  in  scientific 

apparatus. 

Very  good  microscopes  can  be  bought  for  twenty-five  dol- 
lars and  up,  and  no  teacher  should  think  of  teaching  physiology 

without  at  least  one  microscope. 

Reference  Books  for  the  Teacher.  —  The  teacher  should 

have  at  hand  for  constant  use  one  or  more  of  each  of  the 

following  sets  of  books  :  — 

ANATOMIES.  —  Quain,  Gray,  Morris,  Heitzmann. 

PHYSIOLOGIES.  —  American  Text-Book  of  Physiology,  Howell ; 
Text-Book  of  Physiology,  Foster ;  Text-Book  of  Human 
Physiology,  Landois  and  Stirling ;  Text-Book  of  Physiology, 
M'Kendrick ;  The  Human  Body,  Martin ;  Human  Physi- 
ology, Waller ;  Animal  Physiology,  Mills ;  Comparative 
Physiology,  Mills ;  Hand-Book  of  Physiology,  Kirke ;  Text- 
Book  of  Chemical  Physiology,  Halliburton. 

PRACTICAL  PHYSIOLOGIES  AND  DISSECTING  GUIDES.  —  Prac- 
tical Physiology,  Foster  and  Langley ;  Practical  Physiology, 
Stirling ;  Anatomical  Technology,  Wilder  and  Gage ;  Phys- 
iology Practicums,  Wilder ;  Dissection  of  the  Dog,  Howell ; 
A  Laboratory  Guide  in  Physiology,  Hall ;  Dissection  of  the 
Cat,  Gorham  and  ToWer ;  Zodtom,y,  Parker. 

WORKS  ON  HYGIENE.  —  Treatise  on  Hygiene  (2  vols.)  Steven- 
son and  Murphy ;  Text-Book  of  Hygiene,  Rohe  ;  Practical 
Hygiene,  Coplin  and  Bevan ;  Ventilation  and  Heating, 
Billings ;  Practical  Dietetics,  Thompson ;  Care  of  the  Sick, 
Billroth;  Hand-Book  of  Nursing,  New  Haven  Training- 
School  for  Nurses ;  Text-Book  of  Nursing,  Clara  Weeks- 
Shaw  ;  Nursing :  its  Principles  and  Practice,  Isabel  Adams 
Hampton. 

THE  USE  OF  THE  MICROSCOPE.  —  Practical  Methods  in  Micro- 
scopy, Clark ;  The  Microscope  and  Microscopical  Methods, 
Gage ;  The  Microtomist' s  Vade-Mecum,)  Lee. 


TO    THE   TEACHER.  ix 

DICTIONARIES.  —  For  the  definition  and  pronunciation  of  tech- 
nical terms  consult  The  Century  Dictionary,  or  Gould's 
Illustrated  Dictionary  of  Medicine. 

Methods  of  Instruction.  —  What  we  wish  to  have  the 
pupil  learn  is  the  natural  action  of  each  organ,  that  he  may 
understand  how  to  keep  it  in  good  working  order.  Now  a 
very  common  way  of  looking  at  the  matter  is  as  follows :  to 
understand  the  action  we  must  first  know  the  structure.  So 
the  anatomy  is  first  studied.  But  the  child  has  little  natural 
interest  in  anatomy,  and,  in  fact,  he  needs  to  know  compara- 
tively little  of  it  to  understand  the  working  of  many  of  the 
organs.  If  we  can  rouse  in  his  mind  the  question,  "What 
work  has  this  part  to  do,  and  how  does  it  do  that  work  ?  "  we 
shall  have  a  good  starting-point,  especially  if  we  have  really 
created  in  his  mind  a  desire  to  get  the  true  answer  to  the  question. 
An  older  student  may  learn  a  good  deal  of  anatomy  patiently 
keeping  in  mind  that  it  is  the  function  of  the  organ  he  is  seek- 
ing after  all,  but  the  younger  mind  has  not  this  long  foresight 
and  patience.  So,  if  we  fail  to  interest  him  at  the  start,  we 
are  likely  to  fail  in  getting  him  to  do  the  work  in  the  proper 
way. 

This  method  of  presenting  a  series  of  problems  for  the 
student  to  work  out  under  the  guidance  of  the  teacher  is  almost 
sure,  with  a  teacher  of  any  skill  whatsoever,  to  give  good  re- 
sults. Let  us  suppose  the  question  to  have  been  roused  in  the 
child's  mind,  "How  do  I  raise  my  forearm,  as  in  taking  a 
mouthful  of  food  ?  "  we  may  proceed  as  follows  :  — 

1.  Observation  of  the  body.     Ask  each  pupil  to  feel  the 
front  of  his  upper  arm.     He  observes  certain  changes  there. 
(See  directions  in  Chapter  II.) 

2.  Dissection.     A  leg  of  a  rabbit,  or  a  sheep  shank,  may  be 
brought  into  the  class-room,  and  the  form  and  general  relations 
of  a  muscle  seen. 


x  TO   THE  TEACHER. 

3.  If  a  good  model  of  the  arm  can  be  obtained,  it  will  prove 
a  fair  substitute  for  the  muscle  of  some  other  animal.     (To 
show  muscle  action  use  a  frog.) 

4.  In  the  absence  of  a  muscle,  or  a  model  of  a  muscle,  a 
drawing  may  be  used.     This  is  good  as  a  review,  especially  as 
the  parts,  properly  labeled,  are  all  before  the  eye  at  one  time. 
The  teacher  should  always  keep  a  supply  of  colored  crayons ; 
as  color  is  a  great  aid,  especially  where  there  are  several  parts 
to   be    shown  having   different   colors.      Good   physiological 
charts  are  very  desirable,  but  often  a  rude  drawing  made  by 
the   teacher   will    serve  a   better   purpose.      The    completed 
drawing,  as  shown  in  the  chart,  especially  where  many  parts 
are  shown,  is  apt  to  be  confusing.     Whereas,  if  the  teacher 
makes  the  drawing,  bringing  out  one  point  at  a  time,  and 
labeling  it  as  he  draws  it,  the  object  seems  to  grow  under  his 
hand,  and  there  is  none  of  the  confusion  that  comes  when  the 
whole  thing  is  thrust  upon  the  sight  and  mind  at  once. 

5.  Mechanical  contrivances  aid  the  teacher.     The  bones 
of   the    arm   may   be   connected    by   rubber   to   imitate   the 
action  of  the  muscle.     (See  directions  in  Chapter  II.) 

6.  The  microscope  may  be  used  to  show  the  minute  struc- 
ture of  muscles. 

7.  The  chemistry  of  many  of  the  actions  of  the  body  may 
often  be  illustrated  by  very  simple  experiments. 

The  teacher  and  the  pupil  should  work  together  to  find  the 
answer  to  the  questions  raised,  to  solve  problems  which  the  skill- 
ful teacher  will  make  to  appear  to  present  themselves. 

The  above  are  some  of  the  most  helpful  modes  of  proce- 
dure. In  some  cases  one  mode  of  procedure  may  prove  more 
helpful,  in  another  case  another  way. 

So  far  as  possible  get  the  pupil  to  thinking,  "  How  can  I 
find  out  about  this  ?  "  Probably  some  pupil  in  the  class  will 
suggest  a  good  way  of  trying  to  find  the  answer.  In  this  way 


TO   THE  TEACHER.  xi 

the  pupils  are  made  to  feel  that  they  are  doing  the  work.  The 
wise  teacher  will  generally  endeavor  to  keep  himself  in  the 
background,  like  a  magnet  under  a  paper  making  the  particles 
of  iron  filings  above  take  on  definite  arrangement,  wholly  un- 
conscious of  any  power  acting  upon  them. 

The  study  of  the  functions  of  the  organs  is  the  keynote  of 
interest  in  the  study  of  all  living  things ;  and  the  divorcing  of 
anatomy  from  physiology  is  proving  bad  for  students  in  higher 
grades,  and  infinitely  bad  for  elementary  students.  The  young 
student  will  learn  all  the  anatomy  he  needs  to  know  in  getting 
the  answers  to  the  questions  about  the  functions  of  the  dif- 
ferent organs.  We  must  take  into  account  the  psychological 
principle  that  when  the  mind  is  roused,  where  there  is  interest, 
there  ideas  may  gain  lodgment,  and  take  root  and  grow.  Of 
course  we  may  continue  to  present  the  dry  facts,  or  even  con- 
tinue to  require  the  pupils  to  memorize  the  statements  of  a 
book,  but  this  is  not  learning  the  actions  of  the  body ;  it  is 
merely  "  studying  physiology  "  (to  pass  an  examination),  and 
will  always  furnish  the  absurd  statements  above  referred  to, 
—  merely  a  jumble  of  words. 

Of  course  the  teacher,  or  some  of  the  more  advanced  pupils, 
will  prepare  the  more  difficult  dissections.  If  possible  save 
the  best  dissections  in  alcohol.  They  will  many  times  serve 
when  fresh  material  cannot  be  obtained,  and  often  in  review 
when  some  point  needs  to  be  brought  up  anew. 

If  the  physiology  comes  in  the  winter  term  the  teacher 
should  lay  in  a  supply  of  frogs  in  the  fall  for  demonstrating 
muscle  action,  the  action  of  the  nerves,  reflex  action  of  the 
spinal  cord,  circulation  of  the  blood,  etc.  It  is  almost  impos- 
sible to  dispense  with  the  frog,  if  these  points  are  really  to  be 
made  clear.  The  frogs  may  be  easily  kept  in  a  box  in  a  cellar, 
pouring  a  little  water  over  them  every  day  or  two.  They  will 
not  need  food,  for  at  this  time  of  the  year  they  are  naturally 


Xii  TO   THE   TEACHER. 

dormant.     The  teacher  should  plan  his  work  long  beforehand, 
that  he  may  have  plenty  of  time  to  procure  needed  material. 

Notes  and  Drawings.  —  The  student  should  make  care- 
ful notes  of  all  his  work  in  a  note-book  devoted  to  this  sub- 
ject. These  notes  should  be  accompanied  by  drawings  of  the 
dissections  and  copies  of  diagrams  placed  on  the  blackboard 
by  the  teacher,  and  of  charts  shown  in  the  class-room.  These 
drawings  should  be  made  in  color,  using  water  colors,  where 
it  will  make  the  matter  more  clear,  as  in  the  subject  of  the 
circulation  of  the  blood. 

All  the  books  named  at  the  ends  of  the  chapters  should  be 
in  the  school  library,  and  each  pupil  should  be  required  to  read 
at  least  one  in  each  subject.  The  author  has  required  a  re- 
view of  the  books  read  to  be  placed  in  the  note-book. 

It  is  not  necessary  that  all  the  pupils  should  be  reading  on 
the  same  subject  at  the  same  time,  and  in  most  schools  it 
would  be  impossible  to  furnish  enough  duplicate  copies  to 
enable  them  to  do  so.  Have  the  reading  commence  at  the 
beginning  of  the  term,  and  require  each  to  read  a  book  every 
week  or  two,  according  to  a  carefully  made  plan. 

One  convenient  form  of  keeping  the  notes  is  in  the  style 
of  a  diary.  The  work  of  each  day  is  entered  under  its  date, 
whether  this  work  be  of  practical  work  or  of  recitation. 

Reform  in  Nomenclature.  —  The  expressions  "up"  and 
"  down,"  "  front  "  and  "  back,"  are  confusing  when  horizontal- 
bodied  animals,  such  as  cats  and  rabbits,  are  used  to  illustrate 
human  anatomy  (and  we  must  use  such  forms)  ;  we  should 
use  these  terms :  anterior  meaning  toward  the  head  ;  poste- 
riory toward  the  tail ;  dorsal,  toward  the  region  of  the  back ; 
ventral,  toward  the  region  of  the  belly  ;  lateral,  toward  either 
side ;  proximal,  toward  the  central  axis  of  the  body ;  distal, 
away  from  the  central  axis  of  the  body.  Right  and  left  refer 
to  the  right  and  left  of  the  animal  and  not  of  the  student. 


TO    TI1E   TEACHER.  Xlll 

The  very  common  term  "  blood  vessel  "  is  exceedingly  in- 
appropriate. It  suggests  a  receptacle,  not  a  tube,  as  it  really 
is.  Especially  with  children  we  ought  to  employ  terms  that 
are  significant,  instead  of  terms  that  are  either  meaningless  or 
actually  misleading.  So  the  term  "  alimentary  canal,"  while 
less  objectionable,  is  not  so  appropriate  as  digestive  tube  or  food 
tube.  These  reforms  are  especially  desirable  when  we  intro- 
duce the  study  of  the  human  body  into  the  lower  grades  of 
school  work.  If  the  terms  used  are  full  of  meaning  they  will 
help  to  fix  the  idea,  instead  of  calling  away  the  attention  in 
effort  of  memory  to  keep  its  grip  on  a  new  word.  A  flood  of 
new  and  meaningless  terms  tends  to  discourage  the  child,  and 
to  deaden  his  interest.  Foster  (one  of  the  very  foremost  of 
physiologists)  sets  the  good  example  of  substituting  spinal  bulb 
for  the  long  and  cumbersome  term  medulla  oblongata.  Tho- 
racic should  be  substituted  for  dorsal  in  such  cases  as  "  dorsal 
vertebrse ; "  we  ought  to  say  thoracic  vertebrae.  Precaval  and 
postcaval  veins  we  should  say,  instead  of  anterior  vena  cava, 
posterior  vena  cava. 

Relative  Value  of  Topics.  —  The  relative  value  of  the 
different  topics  ought  to  be  considered.  For  instance,  most  of 
the  elementary  text-books  of  physiology  pay  an  undue  amount 
of  attention  to  the  bones,  when  we  consider  to  what  a  slight 
extent  a  knowledge  of  bones  aids  in  preserving  health.  It 
would  seem  sufficient  to  have  the  skeleton  present  (or  some 
of  the  separate  bones,  if  the  whole  skeleton  cannot  be  ob- 
tained), and  to  refer  to  it  in  connection  with  the  study  of 
the  more  important  organs.  The  bones,  for  the  most  part, 
play  a  wholly  subordinate  part  in  the  work  of  the  body,  be- 
ing passive  in  their  action,  serving  as  levers,  for  protection, 
etc.  Therefore,  when  the  muscles  arid  motion  are  studied, 
let  the  bones  be  introduced,  to  show  that  they  act  as  levers 
in  applying  the  force  of  the  muscle ;  when  the  brain  is 


XIV  TO   THE   TEACHER. 

studied,  look  at  the  brain  case,  etc.  The  bones  by  them- 
selves are  a  pretty  dry  subject;  and  the  teacher  must  not 
allow  the  class  to  lose  its  interest  for  one  day  even,  or  he 
may  never  recover  that  interest. 

Order  of  Topics The  order  of  topics  is  a  most  important 

matter  in  the  study  of  physiology.  We  should  not  only  try 
to  begin  with  the  study  in  such  a  way  as  to  get  and  hold  the 
interest ;  the  topics  ought  to  be  arranged  in  such  an  order  that 
beginning  with  what  is  simple  we  may  proceed  by  an  easy  and 
natural  gradation  to  that  which  is  more  difficult,  so  that  the 
earlier  topics  shall  prepare  the  way  for  the  latter.  Of  course 
the  study  of  any  part  of  the  body  throws  light  upon  the  study 
of  every  other  part.  Still,  it  is  possible  to  make  such  arrange- 
ment that  the  topic  presented  first  be  of  such  a  nature  as  best 
to  explain  itself,  to  stand  alone,  so  to  speak,  and  to  leave  till 
later  the  study  of  actions  that  directly  depend  on  many  others, 
and  that  cannot  be  explained  without  introducing  those  others. 

For  example,  suppose  we  were  to  begin  with  the  digestion, 
which  is  often  presented  as  the  first  of  the  fundamental,  vital 
processes  of  the  action  of  the  body  (the  bones  and  muscles, 
perhaps,  having  had  a  little  attention). 

In  the  study  of  digestion  we  are  met  by  the  action  of 
muscles  in  masticating  the  food,  in  swallowing,  and  through- 
out the  whole  digestive  tube.  Shall  we  leave  the  explanation 
of  muscle  action,  or  stop  and  take  it  up  ? 

Saliva  is  poured  upon  the  food  in  the  mouth.  Shall  we 
stop  and  explain  the  action  of  a  gland  ?  This  involves  a 
knowledge  of  circulation.  To  understand  how  the  gland  gets 
more  blood  at  this  time,  out  of  which  to  make  the  saliva,  we 
must  understand  the  action  of  the  muscles  in  the  walls  of  the 
arteries  supplying  the  gland.  To  understand  the  control  of 
these  muscles  we  must  know  considerable  of  the  nervous  sys- 
tem. And  so  on  throughout  the  whole  process  of  digestion. 


TO    THE   TEACHER.  XV 

We  meet  difficulties  at  every  step  if  we  have  not  studied  the 
details  of  circulation  and  nervous  and  muscular  action. 

The  nerves  control  not  only  the  muscles,  but  every  activity 
of  the  body.  They  are  the  key  to  the  whole  mechanism.  Why 
should  we  leave  the  study  of  their  work  to  the  very  last, 
especially  since  we  know  that  whatever  is  last  in  a  book  is 
likely  to  be  gone  over  hurriedly  ? 

Throughout  the  book  the  natural  sequence  of  topics  has 
been  studied  with  care,  and  the  relation  of  one  part  to  another 
kept  in  mind. 

The  order  adopted  is  the  result  of  twenty  years'  experience 
in  teaching  this  subject.  After  trying  almost  every  possible 
order  this  one  seems  to  offer  the  "  least  resistance  "  to  the 
progress  of  the  pupil.  The  effort  of  the  teacher  should  be  so 
to  arrange  the  topics  that  the  easiest  should  come  first  and 
thus  readily  lead  the  way  to  the  next,  as  the  first  step  of  the 
stair  makes  it  more  easy  to  reach  the  step  above  it. 

There  is  no  royal  road  to  learning ;  it  is  up-hill  work  at 
best ;  but  the  teacher  has  no  right  to  try  to  lead  the  pupils  up 
the  precipitous  side  of  a  mountain  if  there  is  a  side  where  the 
slope  is  gradual,  where  a  relatively  easy  and  natural  path  may 
be  made. 

"  Instruct  us  where  the  mountain  low  declines, 
So  that  attempt  to  mount  it  be  not  vain. 
For  who  knows  most,  him  loss  of  time  most  grieves." 

DANTE. 


CO^TEI^TS. 


CHAPTER  I.                                                PAGE 
INTRODUCTION 1 

CHAPTER  II. 
MOTION ,     .       9 

Experiments  with  the  Muscles  in  our  own  Bodies.  —  Muscle  and 
Nerve.  —  The  Action  of  Muscle.  —  Structure  of  Muscle. — Impor- 
tance of  Muscles.  —  Laws  of  Muscle  Action.  —  Symmetrical  Devel- 
opment of  Muscles. — Relation  of  the  Muscles  and  the  Bones. — 
Levers.  —  Study  of  one  of  the  Long  Bones.  — Joints.  —  Locomotion. 

CHAPTER  III. 

THE  GENERAL,  FUNCTIONS  OF  THE  NERVOUS  SYSTEM. — SENSA- 
TION AND  MOTION 29 

The  Brain  and  Spinal  Cord  of  the  Cat  or  Rabbit.  —  Structure 
of  Nerves  and  Nerve  Fibers.  —  Cross-section  of  the  Spinal  Cord.  — 
Reflex  Action  of  the  Spinal  Cord  of  the  Frog.  — Nerve  Roots  and 
their  Functions.  — Functions  of  the  Spinal  Cord.  —  Voluntary  In- 
terference with  Reflex  Actions. — The  Nature  of  a  Nervous  Im- 
pulse. —  Harmony  in  Muscle  Action.  — Dependence  of  Nerves  and 
Muscles. 

CHAPTER   IV. 
CIRCULATION  OF  THE  BLOOD 48 

The  Blood  and  its  Work. —  The  Heart-beat  and  the  Pulse.— 
A  Drop  of  Frog's  Blood.  —  The  Circulation  of  Blood  in  the  Web  of 
a  Frog's  Foot.  — Heart  and  Lungs  of  a  Pig,  Sheep,  or  Calf.  —  Dem- 
onstration of  the  Action  of  the  Heart. — Reason  for  Injecting  the 
Arteries. —The  Distribution  of  the  Arteries  and  Veins  in  a  Cat 
or  Rabbit. —The  Action  of  the  Frog's  Heart. —The  Rate  of  the 
Heart-beat.  —  The  Action  of  the  Heart.  —  The  Beat  of  the  Heart.  — 
The  Sounds  of  the  Heart. —Action  of  the  Large  Arteries.  —  Ac- 

xvii      x 


XV111  CONTENTS. 

i-  \-.i; 

tion  of  the  Medium-sized  Arteries.  —  The  Blood-flow  in  the  Cap- 
illaries.—The  Veins. —The  Valves  in  the  Veins.  —  Effect  of 
Pressure  on  the  Veins.  —  Rate  of  Blood-How  in  the  Arteries,  Capil- 
laries, and  Veins. — Nourishment  of  the  Walls  of  the  Heart  and 
Blood-tubes. — Dissection  of  the  Sympathetic  Nervous  System. — 
Control  of  the  Heart  and  Blood-tubes  by  the  Nervous  System. — 
Effects  of  Alcohol  on  the  Circulation.  —The  Blood.  —The  Coagu- 
lation of  Blood.  —  The  Lymph.  —  The  Spleen.  —  Massage. 

CHAPTER  V. 
RESPIRATION 105 

The  Organs  of  Respiration.  —  The  Movements  of  Respiration. 

—  Forces  of  Respiration. — Capacity  of  the  Lungs.  —  Hygiene  of 
Breathing.  —  Respiratory  Sounds.  —  The  Control  of  Respiration. — 
The  Chemistry  of  Respiration.  —  The  Production  of  Heat  and  Mo- 
tion in  the  Body.  — The  Two  Breaths.  — Heating  and  Ventilation. 

—  Breathing  through  the  Mouth.  —  Dead  Dust. — Live  Dust.    - 
Bacteria. 

CHAPTER  VI. 
EXCRETION ,.."...  151 

The  Skin  and  its  Functions. —The  Structure  of  the  Skin.— 
The  Sweat  Glands. — Composition  and  Amount  of  Sweat. — Regu- 
lation of  the  Temperature  of  the  Body  by  the  Skin.  —  Distribution 
of  Heat  in  the  Body.  —  Regulation  of  the  Production  of  Heat  in  the 
Body. — Regulation  of  Bodily  Heat  by  Food  and  Clothing. — Sun- 
shine.—  The  Kidneys.  —  Dissection  of  the  Kidney.  —  Microscopic 
Structure  of  the  Kidney. 

CHAPTER  VII. 
DIGESTION 1G7 

Foods  and  Foodstuffs. —The  Proteids.  —  Proteid-containing 
Foods.  —  Cheese.  —  Fats.  —  The  Carbohydrates  and  Carbohydrate- 
containing  Foods.  —  Salts.  —  Necessity  of  a  Mixed  Diet.  — Tea  and 
Coffee.  —  Alcohol.  —  Tobacco.  —  The  Digestive  System.  —  Organs 
of  the  Abdominal  Cavity.  —  The  Organs  of  Digestion.  —  The 
Teeth.  — The  Kinds  of  Teeth  and  their  Arrangement.  —The  Care 
of  the  Teeth.— Dissection  of  the  Head  of  the  Rabbit.  — Experi- 
ments with  the  Digestive  Liquids.  —  The  Bad  Effects  of  Imperfect 
Mastication.  —The  Process  of  Swallowing.  —  The  Stomach.  —  The 
Intestine.  —  Absorption. — The  Lacteals  and  Lymphatics. — Con- 
stipation.—  Hygiene  of  Digestion.  —  A  Good  Dinner.  —  Taking 
Cold.  —  Bathing.  —  Exercise.  —  Forms  of  Exercise.  —  Boxing. — 


CONTENTS.  xix 

PAGE 

Ledger  Account  of  the  Body  and  its  Organs.  —  A  Living  Eddy. 

Fat.  —  Glycogen.—  Nutrition.  —  The  Indestructibility  of  Matter. 

—  The  Indestructibility  of  Force. 

CHAPTER  VIII. 
THE  BKAIN ... .253 

Directions  for  Preparing  the  Brain  of  the  Cat  or  Rabbit.  — 
Study  of  the  Brain. —  The  Cranial  Nerves.  —  The  Functions  of  the 
Cranial  Nerves.  — The  Cerebrum  and  its  Functions. — Location  of 
Brain  Functions.  —  Functions  of  the  Cerebellum.  —  The  Spinal 
Bulb.  —  Blood  Supply  of  the  Brain.  —  Brain  Work  and  Brain  Rest. 

—  Nerve  Stimuli.— The  Nature  of  Sensation.— The  Relative  Na- 
ture of  Sensations.  —  Effects  of  Alcohol  on  the  Nervous  System. — 
Moral  Deterioration  Produced  by  Alcohol.  —  Narcotics. — Opium. 

—  Hashish.  —  Habits. 

CHAPTER  IX. 

THE  SPECIAL  SENSES 284 

General  Sensations  and  the  Special  Senses.  —  What  We  Learn 
by  Touching  Objects.  —  Nerve-endings  in  the  Skin.  —  The  Sense  of 
Touch.  —  The  Pressure  Sense.  —  The  Localization  of  Touch  Sensa- 
tions. —  Illusions  of  Touch.  —  The  Temperature  Sense.  —  The  Mus- 
cular Sense.  — Pain.  — Hunger  and  Thirst.  — The  Sense  of  Taste. 

—  The  Sense  of  Smell. —  The  Sense  of  Sight.— The  Muscles  of  the 
Eyeball.  —  External  Parts  of  the  Eye.  —  Dissection  of  the  Eye. — 
The  Retina.  — The  Center  of  Distinct  Vision.  —  Protection  of  the 
Eye.  —  Adjustment  of  the  Lens  for  Seeing  at  Different  Distances. 

—  The  Blind  Spot.  —Regulation  of  the  Amount  of  Light  Admitted 
into  the  Eye.  —  Color  Sensations.  — Color  Blindness.  —  Stereoscopic 
Vision. — Duration  of  Impressions  of  Light. — The  Care  of  the 
Eyes.  — The  Sense  of  Hearing. —The  Equilibrium  Sense.  — The 
Care  of  the  Ear. 

CHAPTER  X. 
THE  VOICE 320 

The  Larynx  of  the  Calf. — Dissection  of  Larynx. — Voice  and 
Speech. 

CHAPTER  XI. 
ACCIDENTS 328 

How  to  Stop  Flow  of  Blood  from  Wounds.  —  Bleeding  from 
the  Nose.  —  Burns.  —  Fainting.  —  Broken  Bones.  —  Sunstroke.  — 
Treatment  of  the  Drowned.  — Suffocation  in  Wells.  —Poisons  and 


XX  CONTENTS. 

PACK 

their  Antidotes.  —  Wounds  from  Thorns,  Kusty  Nails,   Bites  of 
Cats,  Dogs,  etc.  — Snake  Bites.  — The  Sick-room. 

CHAPTER  XII. 
THE  SKELETON 346 

The  Skeleton  as  a  Whole.  —  Axial  Skeleton. — Appendieular 
Skeleton.  —  Study  of  Vertebrae.  —  Microscopic  Structure  of  Bone. 
—  The  Chemical  Composition  of  Bone.  —  Hygiene  of  the  Bones 
and  Joints. 

APPENDIX  A. 
FOODS  AND  COOKING .357 


APPENDIX  B. 
ANTISEPTICS  AND  DISINFECTANTS 377 

APPENDIX  C. 
TABLES  OF  STATISTICS,  ETC 380 


GLOSSARY 389 


PHYSIOLOGY, 

EXPERIMENTAL    AND    DESCRIPTIVE. 


CHAPTER   I. 

INTRODUCTION. 

Is  it  not  a  splendid  thing  to  be  well  and  strong  ?  To  be 
full  of  bounding  health  ?  To  "  feel  one's  life  in  every  limb  "  ? 

Who  does  not  desire  to  prolong,  so  far  as  possible,  this 
condition  characteristic  of  youth  ? 

Is  it  not  a  pity  that  in  so  many  persons  health  begins  to 
break  down  in  middle  life  ?  That  when  the  mind  is  begin- 
ning to  ripen,  the  body  should  begin  to  decay  ?  Our  later 
years  ought  to  be  our  better  years.  Our  mental  strength  and 
maturity  should  then  enable  us  to  give  back  to  the  world 
something  for  what  it  has  given  us ;  for  in  the  earlier  years 
the  individual  is  constantly  receiving,  and  making  little  re- 
turn. But  bodily  strength  and  vigor  are  necessary  in  order 
that  a  rich^and  ripe  mind  may  exert  its  influence  upon  the 
world.  If  the  days  are  filled  with  pain,  if  there  is  feeble- 
ness of  body,  one  is  likely  to  become  a  burden  to  the  world, 
instead  of  a  bearer  of  its  burdens.  Witness  Holmes  and  Glad- 
stone as  examples  of  men  who  took  excellent  care  of  them- 
selves and  were  able  to  continue  their  work  in  a  ripe  old  age. 

An  animal,  living  in  a  state  of  nature,  may  keep  well  and 
live  its  natural  period  of  life  without  knowing  anything  about 
the  laws  of  health.  But  as  students  or  indoor  workers,  many 

1 


2  INTRODUCTION. 

of  us  lead  a  sedentary  life;  we  are  not  natural,  but  oftei. 
highly  artificial,  in  our  mode  of  living.  We  move  about,  but 
little,  whereas  the  animal  abounds  in  motion.  We  concen- 
trate our  energy  upon  mental  effort,  thus  diverting  a  large 
share  of  our  sum  total  of  energy  away  from  the  process  of 
nutrition.  We  often  shut  ourselves  up  in  rooms  too  nearly 
air-tight.  We  eat  poorly  chosen  and  ill-prepared  food.  We 
devour  it  in  haste,  often  when  we  are  in  a  condition  unfit  for 
taking  food.  In  short,  we  too  frequently  disobey  the  laws  of 
Nature.  Now,  Nature  punishes  every  violation  of  her  laws. 
She  never  forgives,  never  forgets.  Whether  we  trespass  in 
ignorance  or  wittingly,  she  punishes.  But  while  Nature  pun- 
ishes disobedience,  she,  on  the  other  hand,  gives  rewards  for 
obedience  to  her  laws.  Health  and  happiness  are  her  re- 
wards. Are  they  not  sufficient  ?  We  may  abuse  her  kind- 
ness ;  but  she  never  sleeps,  never  fails  to  notice.  We  may, 
for  a  time,  think  we  are  to  escape  ;  but  we  find  the  punish- 
ment, though  delayed,  perhaps  the  more  severe. 

The  out-of-door  worker  may  not  suffer  so  much  from  igno- 
rance in  these  matters.  From  the  character  of  his  occupa- 
tion, he  to  a  certain  extent  is  obliged  to  obey  Nature.  He 
gets  enough  fresh  air.  His  bodily  exertion  generally  brings 
a  hearty  appetite,  vigorous  digestion,  active  circulation  of  the 
blood.  Still,  he  would  greatly  profit  by  knowing  something  as 
to  the  nature  of  his  food,  its  wholesomeness  or  unwholesome- 
ness.  The  fact  that  he  gets  along  fairly  well  is  no  proof  that 
he  always  does  the  best  thing.  His  natural  mode  of  life  may 
keep  him  in  tolerably  good  condition  in  spite  of  his  violation 
of  certain  laws  ;  but  he  could  undoubtedly  learn  much  as  to 
economy  in  the  purchase,  preparation,  and  proper  combination 
of  foods. 

But  with  those  of  us  who  strive  to  lead  "  the  intellectual 
life,"  the  price  of  our  culture  is  high.  We  often  do  so  at  the 


IN  TR  01)  UCTION.  3 

expense  of  animal  vigor.  Unless  we  give  care  to  the  matter 
of  exercise,  the  blood  circulates  too  slowly,  the  appetite  and 
digestion  are  likely  to  become  somewhat  dull,  and  the  whole 
body  suffers. 

In  regard  to  any  machine  of  man's  invention  we  know  that 
we  must  keep  it  in  good  running  order  if  we  would  have  it  do 
good  work,  or  last  long.  We  must  keep  a  machine  clean,  well 
oiled,  and  not  work  it  too  hard.  Are  not  our  bodies  worth 
equal  care  ?  If  some  part  of  a  machine  is  broken,  we  may 
replace  it  at  moderate  expense ;  but  none  of  the  vital  organs 
can  be  replaced.  We  may  get  a  new  mainspring  for  a  watch, 
but  we  cannot  get  a  new  stomach  or  lungs. 

In  the  deacon's  "  One-Hoss  Shay,"  all  the  parts  were  equal 
in  strength  and  durability,  so  that  it  went  to  pieces  — 

"All  at  once,  and  nothing  first, 
Just  as  bubbles  do  when  they  burst." 

In  our  bodies,  usually  some  organ  is  weaker  than  the  others. 
If  this  be  true  of  one  of  the  more  important  organs, — the 
heart,  liver,  stomach,  lungs,  kidneys,  —  then  the  whole  organ- 
ism must  stop,  because  no  substitution  can  be  made.  Since 
most  of  us  inherit  weakness  of  some  organ,  it  behooves  us  to 
find  out  what  forms  of  disease  have  afflicted  our  ancestors, 
and  then  to  guard  carefully  the  weakest  part.  A  person  may 
be  strong  in  all  the  organs  but  one,  and  yet  break  down  ; 
whereas  a  person  apparently  feeble,  yet  well  balanced,  may 
live  longer,  and  have  much  better  health.  In  fact,  great 
strength  is  often  a  source  of  great  weakness.  If  one  has 
powerful  muscles,  and  overworks  them,  he  may  overstrain  the 
heart,  and  consequently  break  down. 

The  student  ought  to  have  his  hours  for  exercise  just  as 
regularly  as  his  hours  for  study  ;  and  it  is  a  matter  of  con- 
gratulation that  so  many  of  our  educational  institutions  insist 


4  IN  TR  OD  UCTION. 

on  physical  training  as  much  as  on  any  other  part  of  the 
curriculum. 

Left  to  himself,  many  a  student  becomes  absorbed  in  his 
study,  and  neglects  his  body.  Others  may  run  to  the  oppo- 
site extreme.  All  should  be  under  proper  direction  and  con- 
trol. There  are  so  many  cold  and  stormy  days  in  this  climate 
that  the  gymnasium  is  a  necessity  for  educational  institutions. 
It  is  a  fine  thing  that  athletic  sports  of  all  kinds  are  now 
much  in  vogue.  They  may  be  overdone,  but  time  will  right 
this.  It  is  to  be  hoped  that  good  health  will  never  again 
be  out  of  fashion  for  young  women  as  well  as  for  young 
men. 

The  student  who  "hasn't  time"  to  play  tennis,  or  ball,  or 
something  of  the  sort,  is  likely  to  lose  the  time  at  the  other 
end  of  his  life.  The  student  or  other  indoor  man  who  can- 
not take  his  hour  a  day  for  recreation  is  often  extremely 
short-sighted.  One-tenth  of  his  time  thus  employed  may 
double  the  length  of  his  life,  and  make  it  very  much  more 
enjoyable. 

The  student  who  cannot  take  time  to  stop  study  for  exer- 
cise is  about  as  wise  as  the  woodsman  who  has  not  time  to 
stop  and  sharpen  his  ax.  He  persists  in  trying  to  learn  his 
lesson  with  a  dull  brain.  If  he  can  be  induced  to  sharpen  his 
brain  by  exercise,  he  will  find  how  much  time  he  can  save  by 
"  wasting"  a  little  in  play. 

Aside  from  the  above  considerations,  the  human  body  is 
worthy  of  study  for  its  own  sake.  Viewed  simply  as  a  mech- 
anism, it  is  wonderful.  Each  organ  is  so  well  adapted  to  its 
work,  and  all  the  organs  work  so  harmoniously  through  their 
connection  and  control  by  the  nervous  system,  that  we  never 
cease  to  admire.  We  admire  a  doll,  or  other  toy,  so  ingen- 
iously constructed  that  it  can  move  its  eyes,  or  walk  a  short 
time  after  being  wound  up.  We  admire  a  mechanism  that 


INTRODUCTION.  5 

can  rudely  imitate  the  human  voice.  But  this  live  mechan- 
ism, which  is  self-winding,  self-regulating,  self-repairing,  self- 
directing,  amazes  us. 

We  take  up  the  study  of  the  human  body  mainly  that  we 
may  learn  how  to  preserve  health ;  the  science  of  health  is 
Hygiene. 

In  order  to  keep  the  various  organs  in  good  order  we  must 
know  what  their  natural  work  is,  and  how  they  do  it ;  the 
science  of  the  action  of  the  body  and  its  parts  is  Physiology. 
The  work,  or  action,  of  each  part,  or  Organ,  is  its  Function. 

In  order  to  understand  the  working  of  each  organ  it  is 
usually  necessary  to  know  something  of  its  construction ;  the 
science  of  structure  is  Anatomy.  But  we  do  not  need  to  go 
far  into  anatomy  to  get  a  fair  knowledge  of  the  manner  in 
which  our  organs  do  their  work.  The  surgeon,  of  course, 
must  be  able  to  locate  accurately  the  various  blood  tubes, 
nerves,  muscles,  etc.  All  we  shall  need  to  know  of  anatomy 
is  the  general  structure  of  the  body  and  of  some  of  the  more 
important  organs,  such  as  the  heart  and  lungs,  the  larynx, 
the  eye,  etc.  It  is  fortunate  for  us  that  these  organs  in  the 
sheep,  pig,  and  cow  are  so  nearly  like  our  own  that  they 
serve  admirably  in  enabling  us  to  understand  ourselves. 

We  know  that  any  organ  is  composed  of  several  different 
kinds  of  material.  For  instance,  in  a  slice  across  a  ham  we 
see  the  skin  on  the  outside,  then  fat  and  lean  and  bone. 
These  "  primary  building  materials"  of  the  body  we  call  Tis- 
sues. These  different  tissues  we  shall  study  as  we  come  to 
them. 

The  whole  body  is  made  up  of  small  particles  called  Cells, 
comparable  to  the  bricks  in  a  house.  These  cells  are  of  vari- 
ous shapes  in  the  different  tissues.  With  the  blade  of  a  very 
dull  knife,  or  the  handle  of  a  scalpel,  gently  scrape  the  inside 
of  the  cheek.  Place  a  little  of  the  white  scraping  on  a  slide 


6  INTRODUCTION. 

in  a  drop  of  water,  cover  with  a  coverslip,  and  examine  under 
a  quarter-inch  objective.  Many  cells  will  be  seen,  some  of 
them  showing  nuclei.  -Compare  these  cells  with  the  accom- 
panying figure. 

In  the  active  tissues  the  cells  are  alive,  and  each  cell 
may  be  considered  as  like  the  Ameba,  a  little  mass  of  living 
jelly-like  substance  called  Protoplasm.  Within  this  is  a  small, 
rounded  part  called  the  Nucleus.  Most  of  the  cells  of  the 
body  differ  from  the  Ameba  in  having  a  distinct  outer  cover- 
ing or  Cell-wall.  A  grape  serves  very  well  to  show  what  a 
cell  is  like.  Now,  the  whole  body  is  built  up  chiefly  of  such 
little  cells,  few  of  them  large  enough  to  be  seen  by  the  naked 
eye.  Although  the  cells  are  closely 
packed  together,  each  cell  leads,  in 
one  sense,  an  independent  life.  I>ut 
all  work  together  to  maintain  the  life 

of  the  body    as   a   whole.     The  cell 
Nucleus.  ig  nke  the  individual  in 


Fig.  1.     Epithelial  Cells  from 

the  inside  of  the  Cheek.          a  community.     Each  lives  primarily 
for  itself,  yet  all  work  together  for 

the  good  of  the  whole.     Each  has  its  own  kind  of  work  to 
do,  as  have  the  individuals  of  the  community. 

The  Physiological  Division  of  Labor.  —  We  are  aware 
of  the  advantages  of  division  of  labor  in  a  community.  If 
each  person  learns  to  do  one  thing  well,  all  work  economically 
together  for  the  common  good,  time  is  saved,  and  better  goods 
of  all  sorts  are  produced.  As  a  rule,  civilization  is  at  a  low 
ebb  where  every  individual  is  a  "  jack-of  -all-trades  "  and  mas- 
ter of  none.  In  the  body  there  is  a  division  of  labor  similar 
to  that  of  a  community.  Each  of  the  different  organs  has  its 
own  work  to  do,  and  all  work  together  for  the  common  wel- 
fare. Each  of  the  tissues  is  composed  of  cells  characteristic 
of  that  tissue.  T?he  cells  of  one  tissue  have  certain  properties 


IN  Tit  OD  UCTION.  7 

and  peculiarities  of  form  differing  from  the  form  and  proper- 
ties of  the  cells  of  any  other  tissue.  The  general  structure  of 
all  cells  is  essentially  the  same,  just  as  all  men  are  alike  in 
their  plan  of  structure.  But  one  man  learns  to  do  one  kind 
of  work,  and  sometimes  can  hardly  do  anything  else.  Often 
the  nature  of  his  work  can  be  judged  from  his  appearance. 
With  the  cells,  while  they  all  have  the  same  essential  struc- 
ture, and  have  certain  properties  in  common,  each  has  some 
one  kind  of  work  that  it  can  do  well,  and  to  which  work  it 
devotes  itself.  The  nerve  cells  receive  impressions  from  the 
outer  world,  carry  nervous  impulses,  and  control  the  various 
activities  of  the  body.  The  muscle  cells  have  as  their  one 
work  the  production  of  motion.  All  the  cells  must  take  food 
for  themselves  and  grow.  Each  has  a  birth,  life,  and  death, 
as  each  individual  in  a  community  of  men  ;  and  as  the  com- 
munity endures,  while  the  individual  members  who  compose 
it  are  continually  changing,  so,  in  the  body,  while  the  form 
remains  about  the  same  from  year  to  year,  the  cells  are  con- 
tinually changing,  some  dying,  and  others  taking  their  places. 

In  an  animal  made  of  a  single  cell,  like  the  Ameba,  the  one 
cell  must  do  everything  for  itself.  The  higher  animals  all  be- 
gin their  individual  life  as  an  egg,  which  is,  in  fact,  a  single 
minute  cell.  This  grows  and  divides,  forming  two  cells.  By 
repeated  division  there  accumulates  a  mass  of  cells.  These 
take  on  the  arrangement  peculiar  to  the  kind  of  animal  from 
which  the  egg  came.  But  as  the  cells  increase  in  number  one 
group  of  cells  takes  up  one  part  of  the  work  of  the  body,  other 
cells  another  part  of  the  work,  and  so  on.  An  individual  liv- 
ing alone  (Robinson  Crusoe)  had  to  do  everything  for  himself. 
Just  as  soon  as  this  "  community  of  one  "  became  a  commu- 
nity of  two  by  the  accession  of  Friday,  there  sprang  up  a 
division  of  labor. 

In  studying  history  (sociology)  we  have  to  deal  with,  the 


8  INTRODUCTION. 

individual,  the  community,  the  state,  and  the  nation.  The 
individual  is  a  cell,  the  community  is  a  tissue,  the  state  is 
an  organ,  and  the  nation  is  one  body. 

Let  us  proceed  to  study  the  nature  of  the  individual  cell, 
and  the  combined  actions  of  these  individuals  in  that  commu- 
nity called  the  human  body. 


CHAPTER    II. 

MOTION. 

MOTION  is  the  most  manifest  sign  of  life.  While  we  are 
sitting  still,  as  we  say,  there  are  frequent  slight  motions  of 
the  head,  body,  and  limbs.  Even  during  sleep  the  move- 
ments of  breathing  may  be  seen ;  the  hand  laid  upon  the  chest 
may  feel  the  beating  of  the  heart,  and  the  finger  detect  the 
pulse  in  a  number  of  places. 

When  an  animal  shows  no  motion  whatever  we  conclude 
that  it  is  no  longer  alive.  We  must  move  to  get  our  food, 
or  at  least  to  eat  and  digest  it.  Motion  is  necessary  for 
breathing,  for  circulating  the  blood,  for  getting  rid  of  wastes. 
We  often  move  to  avoid  injury. 

Motion  is  necessary  for  seeing:  we  must  turn  the  face 
toward  the  object  and  open  the  eyelids ;  we  move  the  eye- 
balls;  within  the  eye  are  motions  to  regulate  the  amount  of 
light  admitted,  and  to  adapt  the  eye  for  seeing  at  different 
distances. 

In  feeling,  we  put  forth  the  hand  to  touch  the  object.  In 
tasting,  we  place  the  object  upon  the  tongue,  or  touch  the 
tongue  to  the  object.  In  smelling,  we  sniff;  and  sniffing  is  a 
respiratory  motion. 

In  hearing,  we  usually  turn  the  head,  and  there  is  mo- 
tion in  the  ear  to  adjust  the  parts  to  accurately  distinguish 
sounds. 

In  speech  there  is  motion.  There  is  motion  in  facial  ex- 
pression ;  or  we  may  communicate  by  signs,  as  in  writing,  or 
talking  with  the  hands. 

9 


10  MOTION. 

In  all  these  instances,  both  in  the  reception  of  knowledge 
through  any  of  the  senses  and  of  the  expression  of  knowledge 
through  any  kind  of  language,  spoken  or  written,  or  facial 
expression,  signs,  or  gestures,  some  motion  is  absolutely 
necessary. 

How  are  all  these  motions,  so  essential  to  every  process  of 
life  —  how  are  they  produced  ? 

Experiments  with  the  Muscles  in  our  own  Bodies.  — 

1.  Clasp  the  front  of  the  right  upper  arm;  draw  up  the 
forearm  strongly  and  as  far  as  possible.     Note  what  changes 
are  felt  in  the  Biceps  muscle. 

2.  Repeat  the  experiment,  and  with  the  thumb  and  finger 
feel  the  cord,  or  tendon,  at  the  lower  end  of  the  muscle,  just 
within  the  angle  of  the  elbow. 

3.  Place  a  weight  in  the  hand,  and  repeat  the  act,  noting 
the  condition  of  the  muscle  during  the  experiment ;  also  note 
the  condition  of  the  tendon. 

4.  Span  the  muscle,  placing  the  tips  of  the  fingers  in  the 
angle  of  the  elbow,  and  the  tip  of  the  thumb  as  far  as  you  can 
up  the  arm ;  again  bend  the  arm.    What  change  in  the  muscle 
does  this  show  ? 

5.  Any  muscle  that  bends  a  limb,  as  does  the  biceps,  is 
called  a  Flexor  muscle. 

6.  Clasp   the    back    of    the    right   upper    arm;    forcibly 
straighten  the  arm.     The  muscle  lying  along  the  back  of  the 
arm  is  the  Triceps  muscle.     It  is  called  an  Extensor  muscle 
because  it  extends,  or  straightens,  the  arm. 

7.  Clasp  the  upper  side  of  the  right  forearm  near  the  el- 
bow;  clench   the   right    hand    quickly  and    forcibly;    repeat 
rapidly. 

8.  Notice  the  thick  mass  of   muscle   at  the  base   of  the 
thumb;   pinch  the   forefinger  and  thumb   strongly   together. 
What  changes  can  be  seen  and  felt  ? 


EXPERIMENTS    WITH   OUR   MUSCLES.  11 

9.  Place  the  Land  on  tlie  outside  of  tlie  slioulder ;  raise 
tLe  arm  to  a  horizontal  position ;  repeat  witli  a  weiglit  in  tlie 
Land. 

10.  Stand  erect  witli  tlie  Leels  close  to  each  other,  but  not 
quite  toucliing;  let  tlie  arms  Lang  freely  by  tlie  sides;  rise  .on 
tiptoes,  without  moving  otherwise ;  repeat  twenty  times. 

11.  Place  tlie  tips  of  tlie  fingers  on  tlie  angles  of  tlie  lower 
jaw ;  shut  tlie  teetli  firmly  on  a  piece  of  rubber,  and  note  tlie 
bulging  of  tlie  Masseter  muscles. 

12.  Press  tlie  fingers  on  tlie  temples;  again  shut  the  jaw 
firmly,  and  feel  tlie  action  of  the  Temporal  muscles. 

13.  Make  a  narrow  band  of  paper  tLat  will  snugly  fit  tlie 
forearm  when  the  Land  is  open  ;  now  clencL  tlie  fist  strongly. 

14.  Witli  a  tape-measure  get  tlie  circumference  of  tlie  up- 


Fig.  2.     The  Shortening  and  Thickening  of  the  Biceps  Muscle  in  raising  the 
Forearm. 

per  arm  when  the  arm  Langs  free ;  again  wLen  tLe  forearm  is 
strongly  flexed. 

15.  In  tLe  same  way  measure  tLe  forearm  when  the  Land 
is  open,  and  wLen  tLe  Land  is  clenched. 

By  these  experiments  we  learn  that  when  a  muscle  works 
it  becomes  shorter,  thicker,  and  Larder. 


12  MOTION  —  MUSCLE  AND  NEKVE. 

In  order  to  understand  the  subject  better,  let  us  look  at 
the  muscles  of  a  rabbit's  leg.  The  dressed  rabbits  found  in 
the  markets  will  serve  very  well,  but  it  is  better  not  to  have 
the  skin  removed  until  just  before  studying  the  muscle.  Two 
students  maj7"  conveniently  work  together. 

Muscle  and  Nerve.  —  In  the  hind  limb  of  the  rabbit 
observe  the  heel  cord,  or  Achilles'  tendon,  passing  upward  from 
the  heel  along  the  back  of  the  leg.  The  tendon  is  the  termi- 
nation of  the  calf  muscle,  which  lies  on  the  back  of  the  shin- 
bone.  Trace  this  muscle  toward  the  body,  and  note  that  it 
passes  between  two  large,  flat  muscles,  one  on  the  inner, 
the  other  on  the  outer,  back  part  of  the  thigh.  Separate 
these  two  flat  muscles,  using  mainly  the  handle  of  the  scal- 
pel. Remove  any  fat  that  may  be  in  the  way.  Deeply  im- 
bedded between  these  muscles  is  a  white  cord,  the  Sciatic 
Nerve.  Trace  this  nerve  toward  the  body,  cutting  away  any 
muscles  or  soft  tissue  covering  it.  How  far  can  you  trace  it  ? 

Now  follow  the  nerve  outward.  Is  it  of  the  same  size 
throughout  ?  What  are  its  relations  to  the  muscles  ?  Study 
carefully  the  calf  muscle,  its  shape,  color,  covering,  ends,  etc. 
The  end  by  which  its  tendon  is  attached  to  the  heel-bone  is 
the  Insertion;  the  other,  less  movable  end,  is  the  Origin. 
From  what  bone  does  it  arise,  and  by  how  many  tendons  ? 
Cut  across  the  muscle  at  its  thickest  part,  the  belly  of  the 
muscle,  and  study  its  structure.  Note  that  the  tendons  at 
the  ends  of  the  muscle  are  continuous  with  the  muscle  sheath 
and  with  the  partitions  running  through  the  muscle. 

Pull  the  tendon  toward  the  body :  this  straightens,  or  ex- 
tends, the  foot ;  the  calf  muscle  is  therefore  called  an  Extensor 
muscle.  With  the  handle  of  the  scalpel  loosen  the  muscle  on 
the  front  of  the  shin-bone ;  prove  that  its  action  is  to  bend, 
or  flex,  the  foot.  It  is  a  Flexor.  Find  its  origin  and  in- 
sertion. 


ACTION   OF  MUSCLE.  13 

We  have  now  seen  the  muscles  themselves,  not  covered  by 
skin.  Our  muscles  are  very  much  like  those  of  the  rabbit, 
only  larger.  But  if  we  would  learn  more  fully  the  action  of 
muscle,  we  need  to  go  to  another  animal,  —  the  frog. 

The  Action  of  Muscle.  —  Kill  a  frog  thus  :  Into  a  fruit- 
jar  of  water  put  a  teaspoonful  of  ether ;  immerse  the  frog  in 
it  and  cap  the  jar.  As  soon  as  the  frog  is  motionless  cut  off 
its  head  and  run  a  wire  down  the  cavity  of  the  spinal  column, 
to  destroy  the  spinal  cord.  Cut  through  the  skin  around  the 
base  of  one  of  the  thighs,  and  strip  off  the  skin  from  the 
whole  of  the  limb.  Note  that  the  muscles  are  of  a  pale  color. 
The  muscles  of  a  frog's  thigh  are  nearly  the  same  in  number 
and  arrangement  as  in  man.  Examine  more  thoroughly  the 
calf  muscle ;  the  end  by  which  it  is  attached  below  is  its 
insertion,  and  the  upper  attachment  is  its  origin. 

Sever  the  limb  from  the  body  at  the  hip  joint.  Separate 
the  muscles  along  the  outer  back  part  of  the  thigh,  and  find 
the  white,  thread-like  Sciatic  Nerve.  The  nerve  must  be 
handled  with  great  care ;  it  must  not  be  pinched  or  dragged. 
Carefully  separate  it  from  the  surrounding  muscles,  and  turn 
it  down  upon  the  calf  muscle.  Cut  away  all  the  muscles  of 
the  thigh,  being  careful  not  to  touch  the  nerve  where  it  runs 
down  by  the  knee.  Sever  the  heel  cord  below  the  heel,  and 
separate  the  calf  muscle  from  the  rest  of  the  leg,  leaving 
undisturbed  its  attachment  above ;  just  below  the  knee  cut 
away  the  shin-bone,  with  all  the  muscles  of  the  leg  except  the 
calf  muscle. 

There  should  now  remain  the  Thigh-Bone,  with  -the  Sciatic 
Nerve  running  to  the  Calf  Muscle  suspended  below.  Fasten 
the  thigh-bone  to  some  support,  such  as  a  clamp  or  ring  on  a 
retort  stand.  Attach  a  small  hook  to  the  tendon,  and  suspend 
from  it  a  slight  weight,  such  as  a  small  key. 

Such  a  preparation  is  called  a  Nerve-Muscle  Preparation. 


14 


MOTION. 


It  should  frequently  be  moistened  with  a  .7  per  cent  solu- 
tion of  common  salt  in  water,  culled  Normal  Saline  Solution. 

Now  take  a  sharp  pair  of  scissors,  and  snip  off  the  shortest 
possible  portion  of  the  upper  end  of  the  sciatic  nerve.  If 
the  muscle  is  closely  watched  at  the  time  when  the  nerve 
is  cut,  it  will  be  seen  to  thicken  and  shorten,  and  to  lift  the 
weight.  If  the  muscle  be  held  between  the  thumb  and  finger 
while  the  nerve  is  pinched  (and  the  scissors  are  the  surest 
pinchers)  it  will  be  felt  to  harden. 

This  experiment  should  be  repeated,  varying  the  weight, 
until  it  is  made  very  clear  that  when  the  nerve  is  stimulated 


Sciatic  Nerve 


SHORTENED 


ELONGATED 


Fig,  3.     Action  of  the  Calf  Muscle  of  the  Frog,  showing  the  Relations  of  the 
Sciatic  Nerve. 


the  Muscle  Shortens  (which  is  the  most  important  fact 
the  action),  thickens,  and  grows  harder. 

Structure  of  Muscle.  —  Chipped  beef  shows   well 
structure  of  muscle.     Looking  at  a  piece  closely  we  see  ^Bet- 


fcout 
;ljRie 


STRUCTURE  OF  MUSCLE. 


15 


Origin 


Bundle  of  Muscle. Fibers 

I 


uscle  Sheath 


CROSS   SECTION 


Tendon 


Insertion 


LONGITUDINAL   SECTION 


work  of  white  substance;  this  is  the  Connective  Tissue.     In 

the  meshes  is  the  red  muscular  tissue.     The  partitions  which 

run  all  through  the  muscle, 

and    the    cross-sections    of 

which  we  see  in  a  piece  of 

chipped  beef,  are  continuous 

with  the  Muscle  Sheath,  and 

both  are  continuous  with  the 

tendons  at  the  ends  of  the 

muscle.      In    fresh    muscle 

the  sheath  and  the  partitions 

are  nearly  transparent,  and 

are  not  easily  seen.  Whenthe 

meat  is  cooked  or  salted  the 

connective  tissue  becomes 

opaque  and  is  white. 

In  frog's  or  rabbit's  mus- 
cle observe  the  thin,  trans- 
parent membrane  covering  the  muscle,  the  muscle  sheath. 
With  forceps  tear  away  part  of  the 
muscle  sheath.  Tear  the  muscle  to 
pieces,  and  note  its  fibrous  structure. 
Put  a  shred  of  muscle  in  a  drop  of 
normal  saline  solution  on  a  slide,  and 
examine  with  low  power  of  the  micro- 
scope ;  again  examine  with  a  higher 
power.  The  cross-markings,  or  stri- 
ations,  will  be  seen. 

Such  muscle  is  called  Striated   or 
Striped    Muscle.     All  of  the   muscles 
used  in  ordinary  motions  are  of  this 
kind. 
In  well-cooked  corned-beef  the  connective  tissue  is  thor- 


Fig.  4.     The  Structure  of  Muscle. 


Fig.  5.  Two  Muscular  Fibers, 
showing  the  Terminations  of 
the  Nerves. 


16  MOTION. 

oughly  softened,  and  the  muscle  fibers  are  easily  separated. 
Thorough  cooking,  especially  slow  boiling,  will  soften  the  con- 
nective tissue,  and  may  render  palatable  meat  that,  cooked 
otherwise,  would  be  exceedingly  tough  on  account  of  the  large 
amount  of  connective  tissue. 

A  good  way  to  represent  the  structure  of  muscle  is  to  take 
a  number  of  pieces  of  regl  cord  to  represent  the  muscle  fibers. 
Wrap  each  in  white  tissue  paper  a  little  longer  than  the 
thread ;  this  represents  the  individual  fiber  with  its  sheath. 
Lay  a  number  of  these  side  by  side;  wrap  all  in  a  common 
sheath ;  let  the  tissue  paper  project  beyond  the  threads,  and 
here  compress  it  into  a  compact  cylinder;  this  last  corre- 
sponds to  the  tendon.  Instead  of  one  long  fiber  continuous 
through  the  length  of  the  muscle,  there  are  many  short  fibers. 
(See  Fig.  4.) 

The  connective  tissue  forms  a  framework  for  all  the  tissues 
of  the  body ;  and  if  their  working  cells  were  removed,  the  con- 
nective tissue  would  remain  like  the  framework  of  a  squeezed 
lemon,  or  like  the  skeleton  of  a  sponge  after  its  soft  tissues 
are  removed,  and  showing  more  or  less  completely  the  form 
of  the  part.  Connective  tissue,  therefore,  may  be  called  the 
skeleton  of  the  soft  tissues.  Muscle  consists,  then,  essentially 
of  a  collection  of  soft,  transparent  tubes,  filled  with  the  semi- 
fluid muscular  fibers.  By  scraping  the  surface  of  a  steak  with 
a  dull  knife  the  muscular  substance  may  be  obtained,  leaving 
the  connective  tissue.  This  is  a  good  way  to  get  the  nutritious 
part  of  beef  for  an  invalid. 

Importance  of  Muscles.  —  The  muscles  make  up  nearly 
half  of  the  weight  of  the  body.  The  different  materials  of 
which  the  body  is  built  up  are  called  Tissues.  Thus  we  find 
muscular  tissue,  bony  tissue,  nervous  tissue,  etc.  Now,  the 
muscles  weigh  nearly  as  much  as  all  the  other  organs  of 
the  body  taken  together.  This  fact,  of  itself,  should  lead 


LAWS   OF  MUSCLE  ACTION.  17 

us  to  consider  the  muscles  of  high  importance.  Add  to  this 
the  facts  above  noted,  that  the  muscles  are  so  largely  con- 
cerned in  the  nutrition  of  the  body,  the  chief  agents  for  its 
protection,  essential  for  the  reception  of  ideas,  and  absolutely 
indispensable  for  the  expression  of  ideas,  and  we  can  see  the 
reason  for  beginning  the  study  of  physiology  with  the  exami- 
nation of  the  muscles  and  their  action. 

Laws  of  Muscle  Action.  —  The  chief  characteristic  of 
muscle  is  its  ability  to  shorten;  incidentally,  it  at  the  same 
time  thickens  and  hardens.  But  it  does  its  work  by  shorten- 
ing, pulling  on  the  bones  by  means  of  the  strong,  inelastic 
tendons,  thus  producing  motion.  The  muscle  is  ordinarily 
said  to  "  contract ; "  but  as  it  occupies  almost  exactly  the  same 
amount  of  space  at  all  times,  the  word  "  contract "  is  inappro- 
priate. A  muscle  may  be  made  to  shorten  one-third  of  its 
length,  but  probably  never  shortens  that  much  in  the  living 
body. 

A  muscle  cannot  be  kept  shortened  for  any  great  length 
of  time.  If  one  holds  his  arm  out  horizontally  as  long  as 
possible  he  soon  feels  fatigue,  later  pain,  and  he  may  feel 
soreness  in  the  muscle  for  several  days.  The  law  of  muscle 
action  is  to  alternate  periods  of  rest  with  periods  of  action. 
In  many  exercises,  as  in  walking,  the  limbs  act  alternately, 
one  resting  or  recovering  position  while  the  other  works. 

If  we  consider  the  biceps  and  triceps  of  the  arm,  we  see 
that  they  are  compelled  to  act  alternately  if  they  would  do 
effective  work.  They  might  both  shorten  at  the  same  time, 
and  are  made  to  do  so  in  such  an  attempt  as  that  of  holding 
the  arm  rigidly  bent  at  a  right  angle ;  as,  for  instance,  in  wres- 
tling "  square  hold,"  in  which  case  one  wishes  to  prevent  his 
opponent  from  either  pushing  or  pulling  him.  But  while  the 
two  muscles  act  no  motion  is  produced.  When  the  flexor 
shortens  the  extensor  lengthens,  and  vice  versa. 


18  MOTION. 

The  muscles  are  always  slightly  stretched,  as  shown  by 
the  fact  that  when  a  cut  is  made  into  a  muscle  the  wound 
gaps  open ;  the  tension  of  the  muscle  is  further  shown  by  the 
fact  that  when  a  bone  is  broken,  as  in  the  upper  arm  or  thigh, 
the  ends  of  the  bones  slip  by  each  other,  and  the  limb  has  to 
be  strongly  stretched  to  bring  the  ends  back  together.  Mus- 
cles act  better  when  slightly  stretched,  and  probably  need  a 
slight  resistant  action  of  the  opponent  muscle. 

Symmetrical  Development  of  the  Muscles.  —  The 
muscles  of  the  two  sides  of  the  body  are  the  same  in  number 
and  arrangement.  At  birth  they  are  probably  about  equal  in 
size,  weight,  and  strength.  Most  persons  early  become  right- 
handed,  and  the  greater  use  of  the  right  hand  and  shoulder 
makes  the  muscles  of  this  side  larger  and  heavier.  The  mus- 
cles pulling  on  the  bones  slightly  modify  them  in  shape.  The 
whole  body  may  become  noticeably  unsymmetrical.  Most  per- 
sons step  harder  on  one  foot  than  on  the  other,  as  shown  by 
the  sound  of  the  footstep,  and  as  shown  by  the  constant  wear- 
ing of  one  shoe  sole  or  heel  faster  than  the  other.  This  is 
often  caused  by  a  tight  shoe,  or  a  peg  in  the  sole,  or  other 
irregularity,  that  for  the  time  made  it  .painful  or  uncomfort- 
able to  bear  the  whole  weight  on  that  foot.  So  the  habit  may 
be  formed  for  life.  The  shoes  of  children  should  be  carefully 
examined.  Better  throw  away  a  pair  of  shoes  than  make  a 
limper  for  life.  The  majority  of  persons  limp,  though  not 
lame. 

In  very  many  persons  one  shoulder  is  habitually  carried 
higher  than  the  other.  Symmetrical  development  should  be 
carefully  sought,  and  any  tendency  to  a  one-sided  development 
should,  so  far  as  possible,  be  avoided. 

We  should  use  the  left  hand  more.  It  should  not  be  so 
often  "  left."  Surgeons  and  barbers  are  usually  ambidextrous. 
Probably  it  would  not  pay  to  try  to  do  everything  equally 


Deltoid 


Serratus  Magnus 


Rectus  Femoris— 


Tibialis  Anticus 


Extensors  of  the  Hand 
Flexors  of  the  Hand 


Pectoral  is  Major 


Rectus  Abdominalis 


Sartorius 


Vastus   Externus 


Extensors  of  the  Toes 


Ventral  View  of  the  Superficial  Muscles. 


To  face  page  18. 


Extensors  of  the  Hand— 


Latissimus  Dorsi- 


Gluteus  Maximus  •— 


Vastus  Externus-- 


Flexors  of  the  Foot 


Trapezius 


..  Deltoid 


•—Flexors  of  the   Hand 


B'ceps  Cruris 


Gastrocnemius 


Tendo  Achilles 


Dorsal  View  of  the  Superficial  Muscles. 


SYMMETRICAL  DEVELOPMENT.  19 

well  with  either  hand.  From  a  physiological  point  of  view, 
the  use  of  a  typewriter  is  to  be  preferred,  in  that  it  obeys  the 
law  of  muscle  action  in  allowing  periods  of  rest  between 
periods  of  action ;  whereas,  in  holding  a  pen  we  use  one  side 
of  the  body  much  more  than  the  other,  and  keep  certain 
muscles  in  action  nearly  all  the  time. 

There  are  many  advantages  in  being  able  to  use  either 
hand.  The  teacher  may  need  to  stand  on  the  right  side  of  a 
blackboard,  and  therefore  to  use  his  left  hand.  A  ball-player 
loses  time  if  he  can  throw  with  only  one  hand.  In  carving,  in 
shaving,  in  bandaging,  in  administering  medicine,  it  may  be 
necessary  to  use  the  left  hand  skillfully.  The  pianist  and 
the  harpist  use  the  two  hands  about  equally,  while  the  vio- 
linist puts  much  more  skill  into  his  left  hand.  Trainers  of 
athletes  usually  begin  by  developing  the  left  side  of  the  body 
till  it  equals  the  right  in  size  and  strength. 

Our  strength  depends  on  our  muscles.  It  is  a  fine  thing 
to  have  strong,  well-developed  muscles,  not  only  because  they 
give  beauty  of  form,  but  because  extra  strength  and  endurance 
may  be  needed  in  case  of  accident,  to  save  one's  own  life  or 
that  of  others.  In  a  case  of  fire,  the  ability  to  climb,  to  go 
up  or  down  a  rope  "  hand  over  hand,"  may  be  all-important. 
Any  one's  life  may  depend  on  his  ability  to  run  far  and  swiftly, 
to  swim,  to  jump,  to  lift  a  heavy  weight. 

When  we  look  at  the  skinned  carcass  of  an  animal  in  the 
market,  we  observe  that  the  muscles  almost  completely  cover 
the  bones.  The  muscles  are  attached  to  the  bones,  and  act 
upon  them  as  levers,  giving  our  motions  strength,  quickness, 
and  precision.  Without  bones  our  motions  would  be  like 
those  of  an  earthworm  or  slug,  slow  and  uncertain.  The 
muscles,  acting  through  the  bones,  can  lift  a  weight  that 
would  crush  the  muscles  if  laid  directly  upon  them ;  while  a 
bone,  able  to  support  a  heavy  weight  without  being  crushed, 


20  MOTION. 

has  no  power  in  itself.     The  muscles  have  active  strength,  the 
bones  have  passive  strength. 

Since  there  is  such  an  intimate  relation  between  the  muscles 
and  the  bones,  let  us  turn  to  the  study  of  the  latter. 

Relation  of  the  Muscles  and  the  Bones.  —  Suspend 
the  skeleton  from  the  ceiling  in  the  most  open  space  in  the 
room.  Let  the  pupils  study  it,  book  in  hand ;  not  to  learn  the 
names  of  all  the  bones,  but  to  get  a  general  idea  of  the  forms 
and  relations  of  the  different  parts.  It  is  well  to  have  the 
skeleton  constantly  at  hand,  to  show  the  location  of  the  vari- 
ous organs  as  they  are  taken  up  one  at  a  time  during  the 
term.  If  possible,  supply  the  class  with  separate  bones  from 
another  skeleton,  and  let  the  pupils  place  each  separate  bone 
alongside  the  corresponding  one  in  the  complete  skeleton. 

Pass  to  the  skeleton,  and  locate  the  biceps  muscle.  After 
examining  Fig.  2,  show  the  points  of  its  origin  and  insertion. 
Feel  the  biceps  of  your  arm.  Note  that  its  thickest  part  is 
opposite  the  most  slender  part  of  the  bone.  But  at  the  en- 
larged end  of  the  bone  the  muscle  has  narrowed  to  a  slender 
tendon,  which  passes  over  the  joint  to  be  attached  to  the  next 
bone,  thus  giving  more  slenderness,  flexibility,  and  freedom  of 
motion  to  the  joint. 

Take  the  bones  of  the  arm  that  are  articulated  (if  there  is 
not  an  artificial  hinge  at  the  elbow,  one  can  readily  be  made 
of  wire)  ;  put  a  strong  rubber  band  in  place  of  the  biceps 
muscle;  fasten  this  to  the  head  of  the  humerus  by  cords, 
and  by  the  lower  end  to  the  radius  and  ulna,  where  the  rough 
places,  an  inch  or  so  from  the  elbow  joint,  show  the  insertion 
of  the  tendons.  Have  the  rubber  stretched  so  that  when  not 
held  it  will  flex  the  forearm.  This  will  serve  to  show  the 
action  of  the  biceps ;  though  we  must  be  careful  to  bear  in 
mind  that  the  muscle  does  not  pull  the  arm  up  because  it  has 
been  stretched,  as  is  the  case  with  the  rubber.  In  the  case 


RELATION   OF  MUSCLES  AND  BONES.  21 

of  the  muscle,  we  know  that  the  live  muscle  has  the  power 
of  shortening  when  stimulated,  and  in  this  respect  is  totally 
unlike  the  rubber. 

The  action  of  the  bones  of  the  forearm  as  a  lever  (we  say 
lever,  not  levers,  because  the  two  bones  of  the  forearm  move 
as  one  in  flexing  and  extending  the  forearm  upon  the  arm) 
may  perhaps  be  better  understood  by  the  following  considera- 
tions :  If  the  arm  consisted  merely  of  the  biceps,  suspended 
from  the  shoulder,  it  is  evident  that  its  only  action  would  be 
a  straight  pull.  Suppose  the  biceps,  thus  hanging  alone  from 
the  shoulder,  had  a  hook  at  its  lower  end,  it  could,  when  it 
shortened,  lift  a  weight  just  as  far  as  it  shortened,  and  no 
farther.  It  could  not  swing  the  weight  outward,  or  push  it 
upward.  But  from  the  way  in  which  the  biceps  is  attached 
to  the  bones  of  the  forearm,  when  the  muscle  shortens  an 
inch  it  may  move  the  hand  a  foot.  Of  course  the  hand  moves 
much  faster,  and  we  have  a  great  gain  in  speed  by  reason  of 
this  lever  arrangement.  Of  course  we  must  see  that  we  can- 
not lift  so  heavy  a  weight  at  this  faster  rate  as  we  could  at 
the  elbow.  For  instance,  suppose  one  were  to  carry  a  heavy 
basket  with  a  bail  handle  by  slipping  the  arm  through  the 
bail  up  to  the  elbow.  Now,  it  is  evident  that  the  biceps  is 
supporting  the  weight.  If  it  is  as  heavy  as  can  be  held  here, 
we  know  that  we  could  not  hold  the  same  weight  in  the  hand 
with  the  elbow  bent  at  a  right  angle. 

Levers.  —  The  essentials  of  a  lever  are,  a  point  about 
which  the  lever  turns,  which  in  the  body  is  some  joint ;  the 
Power  as  it  is  called,  which  in  the  body  is  a  muscle  pulling, 
and  a  weight  to  be  moved  (not  always  to  be  lifted).  The 
point  about  which  a  lever  turns  is  called  its  Fulcrum.  The 
place  where  the  power  is  applied  is  called  the  Power  (where 
the  muscle  is  attached),  and  the  part  to  be  moved  is  the 
Weight.  In  flexing  the  forearm,  the  weight  is  the  hand,  or  the 


22 


MOTION  —  LEVERS. 


hand  and  what  is  in  it ;  the  fulcrum  is  the  elbow  joint ;  and 
the  power  is  the  point  where  the  tendon  of  the  biceps  is 
attached  to  the  radius.  This  kind  of  a  lever  is  what  the 
books  call  a  lever  of  the  third  class.  The  triceps,  on  the  back 
of  the  arm,  pulls  on  the  projection  of  the  ulna  back  of  the 
elbow.  The  elbow  is  here,  also,  the  fulcrum,  and  the  hand 
(or  the  object  to  be  pushed  by  the  hand)  is  the  weight.  This 
kind  of  lever,  where  the  fulcrum  is  between  the  power  and 
the  weight,  is  called  a  lever  of  the  first  class.  In  raising  the 
weight  of  the  body,  by  standing  on  tiptoe,  we  use  a  lever  of 
the  second  class.  Here  the  ball  of  the  foot  is  the  fulcrum. 
The  weight  is  the  weight  of  the  whole  body,  resting  on  the 
ankle  joint,  while  the  power  is  the  calf  muscle.  We  may  find 
many  examples  of  levers  in  the  body  if  we  look  for  them. 


(1.)  TAPPING    ON    FLOOR          (2.)  RISING   ON    TOE  (3.)  LIFTING    WEIGHT 

Fig.  6.     Three  hinds  of  Levers  as  shown  by  the  Foot. 
P,  Power.    W,  Weight.    F,  Fulcrum. 

The  different  classes  of  levers  may  be  further  illustrated 
by  different  motions  of  the  foot.  In  tapping  the  toes  on  the 
floor  while  the  heel  is  lifted,  or  in  pressing  down  the  ball  of 
the  foot  while  running  the  treadle  of  a  sewing-machine,  we 
have  an  example  of  a  first-class  lever.  In  raising  the  weight 


STUDY  OF  A   LONG   BONE. 


23 


Ball 


Articular    Extremity 


of  the  body  on  tiptoes,  or  as  the  foot  is  used  in  taking  each 
step,  the  foot  is  used  as  a  lever  of  the  second  class.     When 
one  lifts  a  weight  with  the  toes,  the  foot  is  used  as  a  lever 
of  the  third  class.     These  three 
classes   of  levers  are  illustrated 
in  the  accompanying  figures. 

In  the  earthworm  we  have  an 
example  of  what  sort  of  motions 
we  could  execute  without  bones. 
And  even  the  earthworm  has 
spines  that  help  it  in  crawling. 
But  we  see  how  slow  and  rela- 
tively feeble  are  its  movements. 
Compare  these  with  the  rapidity, 
force,  and  precision  of  our  mus- 
cular actions. 

In  the  experiment  with  the 
frog's  muscle  we  saw  what  we 
have  mentioned  as  the  action 
of  a  muscle  by  itself.  We  need 
levers  through  which  the  muscles 
can  act. 

Study  of  One  of  the  Long 
Bones.  —  For  this  take,  prefer- 
ably, a  femur  or  a  humerus.  Let 
us  suppose  we  have  a  femur. 

1.  Observe    its    shape,  —  cy- 
lindrical,   somewhat   curved,   en- 
larged at  the  ends. 

2.  The  ends  have  smooth  places,  where  they  fitted  other 
bones. 

3.  Along  the  sides,  especially  near  the  ends,  are  ridges  and 
projections,  where  the  muscles  were  attached. 


Medullary  Cavity 

Shaft 

Hard  Bone 


—  Spongy  Bone 
Articular    Extremity 

Fig.  7.     Longitudinal  Section  of 
Femur. 


24  MOTION  — JOINTS. 

4.  There  are  small  holes  in  the  bone,  where  blood  tubes 
passed  in  and  out. 

5.  Saw  a  femur  in  two,  lengthwise,  and  make  a  drawing 
showing :  — 

(a)  The  central  marrow  cavity. 

(b)  The  spongy  extremities,  noting  especially  the  directions 
of  the  bony  plates  and  fibers. 

6.  Observe  the  width  of  the  lower  end  of  the  femur,  where 
it  rests  on  the  tibia.     Suppose  these  two  bones  were  as  narrow 
at  their  ends,  where  they  meet  to  form  the  knee  joint,  as  they 
are  at  their  centers,  what  kind  of  a  joint  would  they  make  ? 
Illustrate  by  piling  up  a  number  of  spools  on  end  ;  the  column 
is  more  lightened  than  it  is  weakened  by  the  hollowing  out  of 
the  sides  of  each  spool.     And  the  central  hollow  of  the  spool 
does  not  greatly  weaken  it.     A  given  weight  of  material  has 
more  strength  when  in  the  form  of  a  hollow  cylinder.     Note 
carefully  that  this  is  not  saying  that  a  hollow  pillar  is  stronger 
than  a  solid  one;    but   for  the  same   weight   of  bone  more 
strength  is  given  by  having  it  hollow.     The  bones  combine 
well  two  very  desirable  qualities,  lightness  and  strength. 

If  in  our  column  of  spools  we  place  a  wide  rubber  band 
around  the  junction  of  two  spools,  we  have  something  very 
similar  to  the  Capsular  Ligament,  of  which  we  shall  learn 
something  soon. 

Joints.  —  Use  beef  joints  or  sheep  shanks  for  demonstra- 
tion ;  or,  if  the  work  is  done  by  the  individual  members  of  the 
class,  supply  them  with  the  legs  of  rabbits. 

1.  Cut  into  the  knee  joint.     Observe  the  liquid   Synovia 
that   lubricates   the   joint.     Rub  a  drop  of    it  between  the 
thumb  and  finger. 

2.  Note  the  white,  glistening  bands,  the  Ligaments,  that 
hold  the  ends  of  the  bones  together.     Carefully  study  their 
arrangement.     The   ligaments   are   composed   of   a   form   of 
connective  tissue. 


LOCOMOTION. 


fao  3 


3.  Observe  the  thin  layer  of  Cartilage  over  the  ends  of  the 
bones.     Feel    it.     Cut   off   a   thin    slice.     Consider   how  its 
smoothness    and   elasticity   give   ease 

of  motion,  and    diminish   the    shocks 
that  the  body  receives. 

4.  Thoroughly    clean    one    of   the 
long   bones,   and  study  its  form    and 
parts.     Its  tough  covering  is  the  Peri- 
osteum. 

Locomotion.  —  By  continuing 
such  observations  as  we  made  when 
we  began  to  study  our  motions,  we 
can  analyze  and  understand  many  of 
the  common  movements  which  we 
habitually  make. 

Although  we  are  not  ordinarily 
conscious  of  the  fact,  when  we  are 
standing  still  we  are  using  many  mus- 
cles. The  accompanying  figure  illus- 
trates how  some  of  the  muscles  act  in 
keeping  the  body  upright.  Our  weight, 
or,  we  would  better  say,  the  force  of 
gravity,  is  continually  trying  to  pull 
us  down  to  the  ground.  The  joints 
are  all  freely  movable,  and  hence  as 
soon  as  the  muscles  cease  to  act  prop- 
erly, in  balancing  against  each  other, 
we  lose  our  equilibrium,  and  fall  if 
we  do  not  quickly  regain  it. 

In  walking,  we  lean  forward,  and 
if  we  take  no  further  action  we  fall, 
on  the  ground,  pushing  the  body  forward,  while  the  other  leg 
is  flexed,  and  carried  forward  to  save  us  from  the  fall.     We 


\ 


Fig.  8. 


Action  of  the  Muscles 
in  Standing. 


But  we  keep  one  foot 


26  MOTION  —  LOCOMOTION. 

catch  the  body  on  this  foot,  and  repeat  the  action.  To  show 
how  we  are  really  repeatedly  falling  and  catching  ourselves, 
recall  how  likely  one  is  to  fall  if  some  obstacle  is  placed  in 
the  way  of  the  foot  as  it  moves  forward  to  catch  the  weight 
of  the  body. 

In  running,  the  action  is  more  vigorous.  The  propulsion 
by  the  rear  leg  is  now  greater.  It  gives  such  a  push  as  to 
make  the  body  clear  the  ground,  whereas  in  walking  the  rear 
foot  is  not  lifted  till  the  front  foot  touches  the  ground.  But 
in  running  there  is  a  time  when  both  feet  are  off  the  ground. 

In  similar  manner  we  may  explain  the  action  in  jumping, 
hopping,  etc.  We  should  distinguish  between  motion  and 
locomotion.  In  the  latter  we  move  the  body  from  place  to 
place.  It  is  interesting  to  note  that  our  locomotion  is  pro- 
duced by  reaction.  The  direct  result  of  pushing  downward 
and  backward  with  one  leg  is  simply  to  extend  the  leg.  Or, 
if  there  is  anything  in  the  way,  to  push  that  something  out 
of  the  way.  If  one  walks  on  a  barrel  the  barrel  is  rolled 
backward.  To  show  this  better,  take  two  broomsticks,  and 
lay  them  parallel  a  few  feet  apart ;  lay  a  long  board  across 
them ;  then  try  to  run  along  the  board.  Of  course  one  is 
likely  to  fall,  and  sees  that  the  direct  effect  of  the  effort  is 
simply  to  push  the  board  out  from  under  one's  self.  When 
a  horse  tries  to  spring  forward  in  the  mud,  he  only  plunges 
his  feet  deeper  in  the  mud.  Our  effort  in  progression  is  pri- 
marily an  attempt  to  push  the  earth  out  from  under  us,  and 
it  is  only  by  reaction  that  we  go  forward.  It  is  the  same 
problem  with  the  fish  swimming  forward  by  striking  back- 
ward and  sideways  against  the  water,  and  in  the  case  of  the 
bird,  beating  downward  and  backward  in  the  air.  In  each 
case  progression  comes  only  through  the  mechanical  principle 
of  reaction. 

The  muscles,  then,  make  use  of  the  bones  as  levers      We 


LOCOMOTION.  27 

do  not  ordinarily  carry  handspikes  and  crowbars  with  us ;  we 
get  them  when  we  need  them  :  but  we  carry  these  levers  with 
us  all  the  time.  Hence  the  desirability  of  having  them  as 
light  as  is  consistent  with  the  requisite  degree  of  strength. 
The  body  follows  the  same  law  of  mechanics  that  we  use 
outside  of  the  body.  A  pillar  or  hollow  tube  has  a  greater 
strength  than  the  same  amount  of  material  in  the  form  of  a 
solid  cylinder.  The  long  bones  of  the  limbs  are  hollow ;  and 
near  their  ends,  where  we  have  found  that  they  need  to  be 
enlarged,  we  find  a  spongy  appearance,  where  lightness  and 
strength  are  secured  by  the  interlacing  fibers  and  plates  of 
bony  material. 

As  we  have  seen,  the  part  that  the  bones  play  is  of  a  pas- 
sive nature  j  they  support  the  other  organs,  protect  some  parts, 
and  serve  as  levers  on  which  the  muscles  act.  We  may  not 
call  the  bones  dead  organs,  for  they  receive  blood  and  grow. 
But  the  active  muscles  use  them  as  a  man  uses  a  crowbar,  as 
a  mere  tool.  It  will  therefore  be  more  interesting  to  return 
to  the  muscles,  and  try  to  learn  the  causes  and  conditions  of 
their  activity. 

Have  you  ever  seen  two  persons,  each  using  the  right  hand, 
try  to  sew,  one  holding  the  cloth,  the  other  using  the  needle? 
Would  they  get  along  well  ?  Suppose  one  were  to  hold  the 
needle,  and  the  other  were  to  try  to  thread  it,  each  using  one 
hand  ?  In  dissecting,  suppose  one  holds  a  delicate  object 
with  forceps  while  the  other  uses  the  scissors  ?  Or  that  A 
holds  the  violin  and  does  the  fingering,  while  B  manages  the 
bow  ?  Or  in  so  comparatively  simple  a  matter  as  the  use  of 
the  knife  and  fork  in  eating,  how  if  one  holds  the  piece  of 
meat  with  the  fork  while  the  other  tries  to  cut  it  ? 

Why  is  it  that  the  right  hands  of  two  persons  cannot 
work  so  well  together  as  the  right  and  left  hands  of  one  per- 
son ?  What  connection  is  there  between  the  two,  that  one 


28  MOTION. 

knows  just  what  the  other  is  doing  and  when  it  does  it  ? 
Why  can  two  individuals  never,  with  any  amount  of  practice, 
work  so  in  unity  as  the  parts  of  the  individual  ? 

Let  us  seek  the  answers  to  these  questions  in  the  follow- 
ing lessons. 

RKADING.  —  How  to  Get  Strong  and  How  to  Stay  So,  Blaikie ; 
Sound  Bodies  for  Our  Boys  and  Girls,  Blaikie;  Physiology 
of  Bodily  Exercise,  Lagrange. 


CHAPTER   III. 

THE   GENERAL   FUNCTIONS   OF   THE   NERVOUS 
SYSTEM.  —  SENSATION   AND   MOTION. 

WE  have  seen  that  the  muscles  have  the  power  of  short- 
ening ;  that  in  shortening  they  act  on  the  bones  as  levers  to 
produce  our  varied  motions.  But  what  makes  the  muscles 
shorten  ? 

Some  motions  we  will  to  make.  We  will  to  sit,  to  stand, 
to  walk,  to  run,  to  stretch  out  the  hand,  to  take  pencil  and 
paper,  to  write.  Such  motions,  originating  in  a  brain  activity, 
are  called  Voluntary.  Other  motions  are  Involuntary.  The 
will  does  not  control  the  heart-beat.  Most  persons  cannot 
keep  from  winking  when  a  quick  motion  is  made  toward  the 
face,  even  if  they  know  they  will  not  be  hit.  But  all  of  these 
motions,  whether  voluntary  or  involuntary,  are  dependent  upon 
the  nervous  system.  In  the  experiment  with  the  frog's  mus- 
cle we  made  it  shorten  by  pinching  the  sciatic  nerve.  Let  us 
look  at  the  nervous  system  of  the  rabbit,  which  is  larger  than 
the  frog's,  and  essentially  like  our  own. 

The  Brain  and  Spinal  Cord  of  the  Rabbit.  —  It  will  be 
found  helpful  to  have  at  hand  a  well-mounted  skeleton  of  a 
cat  or  rabbit.  Note  carefully  (a)  the  cavity  of  the  cranium, 
(b)  the  cavity  in  the  spinal  column,  and  (c)  the  sides  of  each 
neural  ring  where  the  bone  is  to  be  cut  by  the  bone  forceps, 
as  indicated  in  Fig.  10. 

It  is  best  to  remove  the  skin  completely  before  beginning 
the  work,  as  the  fur  is  likely  to  be  troublesome. 

Cut  away  the  muscles  from  the  back  of  the  neck  and  along 

29 


30 


NERVOUS   SYSTEM. 


Fig.  9.     Diagram  Showing  Arrangement  of  Nervous  System. 


DISSECTION   OF  THE  SPINAL    CORD. 


31 


the  sides  of  the  backbone.  This  can  be  done  rapidly  by  mak- 
ing long,  deep  cuts  with  the  cartilage  knife  along  the  sides 
of  the  backbone,  in  the  planes  indicated  in  the  accompany- 
ing figure. 

Between  the  skull  and  the  first  vertebra  is  a  space  cov- 
ered by  a  thin  membrane,  through  which  the  Spinal  Cord 
may  be  seen.  Carefully  cut  through  this  membrane,  and  in- 
sert the  point  of  one  blade  of  a  pair  of  bone  forceps  at  one 


Fig.  10.     Diagram  for  Dissecting  Spinal  Cord. 

1.  Cut  along  1 2  with  cartilage  knife. 

2.  Cut  along  3 2  with  cartilage  knife. 

3.  Cut  along  4  with  bone  forceps. 

side  of  the  spinal  cord.  Cut  through  this  side  of  the  arch  of 
the  vertebra ;  repeat  this  on  the  other  side,  and  so  on,  through 
the  whole  length  of  the  spinal  column,  removing  the  dorsal 
parts  of  the  vertebrae,  held  together  in  one  strip  by  the  con- 
nective tissue.  The  bony  cavity  in  which  the  spinal  cord  lies 
is  the  Neural  Cavity. 

The  work  may  be  more  easily  done  if  the  rabbit  is  sup- 
ported on  the  edge  of  a  brick,  or,  better,  on  the  edge  of  a 


32  SPINAL  NERVES. 

short  piece  of  "  two  by  four  "  scantling  nailed  to  a  base-board 
eight  inches  wide  and  a  foot  and  a  half  long. 

Now  look  for  the  Spinal  Nerves,  which  leave  the  spinal 
cord  in  pairs,  right  and  left,  between  the  successive  vertebrae. 
It  will  probably  be  necessary  to  cut  away  considerably  more 
bone  to  expose  the  nerves.  The  whole  of  this  work  requires 
the  utmost  care  and  patience,  and  involves  a  good  deal  of 
hard  muscular  exertion. 

Note  carefully  the  variations  in  the  diameter  of  the  spinal 
cord  in  its  course.  The  anterior  swelling  is  called  the  Cervi- 
cal Enlargement,  and  the  posterior  is  the  Lumbar  Enlargement. 

When  the  spinal  nerves  have  all  been  laid  bare,  count  and 
compare  them  in  reference  to :  — 

1.  Size. 

2.  Intervals  between  successive  pairs. 

3.  Angles  at  which  they  leave  the  spinal  cord. 
Carefully  cut  away  the  bone  around  some  of  the  nerves  in 

the  region  of  the  shoulder,  and  find  the  two  Roots  by  which 
each  nerve  is  connected  with  the  cord,  one  nearer  the  back, 
the  Dorsal  Root,  and  one  nearer  the  ventral  surface  of  the  body, 
the  Ventral  Root.  Trace  these  two  roots,  and  note  that  they 
unite  and  form  a  spinal  nerve. 

On  the  dorsal  root,  just  before  it  joins  the  ventral,  is  a 
small  swelling,  the  Ganglion  of  the  dorsal  root. 

In  the  region  of  the  shoulder  carefully  trace  several  of  the 
nerves  as  they  unite  to  form  the  Brachial  Plexus,  from  which 
nerves  supply  the  fore  limb. 

In  the  region  of  the  hips  trace  several  of  the  spinal  nerves 
to  their  union  in  the  large  Sciatic  Nerve,  which  runs  down  the 
thigh. 

Turn  now  to  the  head,  and  cut  through  the  bone  between 
the  eyes.  Cautiously  working  backward,  the  whole  of  the 
brain  may  be  unroofed.  Great  care  must  be  exercised,  for 


STRUCTURE  OF  NERVES.  33 

here  we  have  one  of  the  softest  of  the  tissues  of  the  body 
lying  very  closely  beneath  one  of  the  hardest.  It  is  possible 
to  do  this  work  with  a  strong  knife,  but  the  bone  forceps  save 
a  vast  amount  of  extra  work.  The  bone  must  be  broken  away 
bit  by  bit. 

Compare  the  color  of  the  brain  with  that  of  the  spinal  cord. 

The  tough  membrane  covering  the  brain  is  the  Dura  Mater, 

The  fore  part  of  the  brain  is  the  Cerebrum.  Note  the 
groove  separating  it  into  the  right  and  left  Hemispheres.  Ob- 
serve the  ridges,  or  Convolutions,  of  its  surface.  The  prolon- 
gations of  the  brain  between  the  eyes  are  the  Olfactory  Lobes. 

Back  of  the  cerebrum  is  the  Cerebellum.  Look  at  the 
human  skull  to  see  whether  there  is  a  bony  partition  corre- 
sponding to  that  which  separates  the  cerebrum  from  the 
cerebellum  in  the  rabbit. 

The  widening  part  of  the  spinal  cord  within  the  skull  is 
the  Spinal  Bulb  (Medulla  Oblongata). 

Make  a  drawing  of  the  brain  and  spinal  cord,  showing  as 
many  as  possible  of  the  points  above  noted.  If  desired,  the 
brain  and  cord,  with  a  short  part  of  each  nerve,  may  be  re- 
moved from  the  body,  and  laid  on  a  cushion  of  cotton  in  weak 
alcohol. 

Structure  of  Nerves  and  Nerve  Fibers.  —  When  we 
trace  the  sciatic  nerve  outward,  we  find  that  it  is  continually 
subdividing.  This  dividing  goes  on  until  the  branches  are 
too  small  to  be  seen  by  the  naked  eye.  Microscopic  examina- 
tion shows  that  a  nerve  is  made  up  of  a  great  number  of 
fibers  bound  together  in  a 'common  sheath  of  connective  tis- 
sues very  much  the  same  as  in  a  muscle.  When  the  nerve 
divides  it  is  found  that,  ordinarily,  there  is  no  true  branching, 
or  forking,  but  that  certain  of  the  fibers  have  simply  sepa- 
rated from  the  rest,  as  in  the  separation  of  the  fibers  in  floss 
silk. 


34  STRUCTURE  OF  NERVE  FIBER. 

An  individual  nerve  fiber  is  too  small  to  be  seen  by  the 
naked  eye,  being  only  about  one  two-thousandth  of  an  inch 
in  diameter.  There  are  two  kinds,  white  and  gray.  A  White 
Nerve  Fiber  consists  of  the  following  parts  :  — 

1.  A  central  strand,  or  core,  of  semi-transparent,  grayish- 
looking  material,  called  the  Axis-cylinder.     This  is  the  essen- 
tial part  of  the  nerve  fiber,  and  does  the  work  of  the  nerve, 
which  is  to  convey  Nerve  Currents,  or  Nerve  Impulses. 

2.  Around  the  axis-cylinder  is  a  layer  of  white,  oily  mate- 
rial, known  as  the  Medullary  Sheath. 

Nerve   Fiber  Sheath 


Axis  Cylinder 


Medullary  Sheath 
Fig.  11.     Structure  of  a  Nerve  Fiber.     (Diagram.) 


3.  Outside  this  is  a  thin,  transparent  sheath  of  connective 
tissue,  essentially  like  the  muscle-fiber  sheath,  the  Nerve-Fiber 
Sheath. 

The  sole  function  of  the  nerve  fiber  is  to  convey  nerve  im- 
pulses. 

Gray  Nerve  Fibers  have  no  medullary  sheath,  but  consist 
simply  of  the  axis-cylinder  and  the  nerve-fiber  sheath.  They 
are  found  principally  in  the  sympathetic  nerves. 

Cross-section  of  the  Spinal  Cord.  —  If  a  thin  slice  of 
the  spinal  cord  be  made  as  shown  in  Fig.  12,  it  will  be  seen 
that  the  central  portion  is  of  a  darker  color  than  the  outer 
part. 

The  central  part  is  known  as  the  Gray  Matter,  in  distinction 
from  the  rest,  which  is  called  the  White  Matter.  The  white 


SPINAL    CORD. 


35 


matter  of  the  nervous  system  is  made  up  of  nerve  fibers  whose 
structure  and  use  we  have  just  considered.  But  the  gray  mat- 
ter has  a  different  structure  and  a  different  function.  Instead 
of  being  made  up  mainly  of  fibers,  it  is  composed  of  cells, 
rounded  masses,  some  of  the  forms  of  which  are  represented  in 
Fig.  13.  Some  of  the  branches  of  these  cells  are  continued, 
and  become  the  axis-cylinders  of  nerves,  and  it  is  asserted 

Dorsal   Septum 


Dorsal  or 
Sensor 
Root 


Ganglion- 


Spinal   Nerve          Ventral  or 
Motor  Root 


Fig.  12.     Cross-section  of  Spinal  Cord. 


that  every  nerve  fiber  begins  as  a  branch  of  some  nerve-cell. 
One  of.  the  best  places  to  see  these  nerve-cells  is  in  the 
gray  matter  of  the  spinal  cord,  near  where  the  ventral  root 
of  the  spinal  nerve  arises.  This  part  of  the  gray  matter  is 
called  the  Ventral  Horn  of  the  gray  matter.  If  this  portion 
be  examined  under  a  moderately  high  power  of  the  micro- 
scope, there  may  be  seen  a  number  of  cells  with  radiating 
branches. 


36 


HE  FLEX   ACT  I  <>X. 


Masses  of  nerve-cells  make  up  Nerve  Centers,  or  Ganglia, 
such  as  we  saw  on  the  dorsal  roots  of  the  spinal  nerves. 
These  also  would  show  under  the  microscope  that  their  chief 
constituent  is  a  collection  of  nerve-cells  which  give  off  one  or 
more  branches. 

The  gray  matter  of  the  spinal  cord  is  considered  a  collec- 
tion of  ganglia.  We  see  that  the  outer  layer  of  the  brain  is 
grayish  in  color.  Within  is  white  matter,  consisting  of  nerve 
fibers  that  connect  the  cells  of  the  gray  layer  with  the  various 


Branched   Processes 


Unbranched  Process,  or 
Axis  Cylinder  Process, 
continued  into  Axis  Cylinder 
of  a  Motor  Fiber 


Fig.  13.     A  Large  Nerve-Cell  from  the  Gray  Matter  of  the  Spinal  Cord. 

parts  of  the  body  through  the  base  of  the  brain,  the  spinal 
cord,  and  spinal  nerves. 

Reflex  Action  of  the  Spinal  Cord  of  the  Frog.  —  Be- 
fore we  experiment  on  the  frog,  let  us  recall  some  facts  that 
we  all  know.  After  a  fowl's  head  is  cut  off  it  " flops"  around 
for  some  time,  and  it  may  even  jump  clear  from  the  ground. 
If  one  takes  hold  of  its  feet  to  pick  it  up,  it  may  begin  to 
struggle  as  if  it  were  trying  to  get  away. 

Now,  we  know  that  the  bird  cannot  feel  anything  after  its 
head  is  cut  off,  not  even  if  a  pin  were  thrust  into  its  body, 


REFLEX  ACTION.  37 

nor  if  its  feet  were  held  in  fire.  So  with  the  frog.  After  its 
head  is  cut  off,  or,  what  amounts  to  the  same  tiling,  its  brain 
destroyed,  it  cannot  feel  anything,  and,  of  course,  cannot  have 
any  pain.  So,  if  in  any  of  the  experiments  with  the  frog  after 
its  head  is  cut  off  it  seems  to  be  suffering  or  attempting  to 
get  away,  remember,  it  cannot  feel. 

Kill  the  frog  as  directed  on  page  13.  As  soon  as  it  is 
motionless,  take  it  out  of  the  jar.  By  bending  its  head,  find 
the  joint  between  the  head  and  the  backbone.  Lay  the  frog 
on  a  board,  and  thrust  the  scalpel  through  the  body  at  the 
joint  just  found,  thus  completely  severing  the  spinal  column 
and  spinal  cord.  Run  a  wire  through  the  opening  thus  made 
into  the  skull,  and  stir  about  to  destroy  the  brain. 

After  a  while  suspend  the  frog  from  a  ring  of  a  retort 
stand  by  a  hook  through  the  jaw. 

1.  With  a  pair  of  forceps  pinch  one  of   the  frog's  toes. 
Now,  if  the  frog  were  alive  it  would  feel  the  pinch,  and  a 
strong  pinch  would  cause  pain.      Now  that  the  brain  is  de- 
stroyed, it  feels  nothing.     Still  it  draws  up  the  foot.     Repeat 
the  experiment  with  the  other  foot. 

2.  Lay  the  frog  on  its  abdomen,  and  dissect  away  the  skin 
from  the  back  of  one  of  the  thighs.     Separate  the  muscles 
along  the  noticeable  groove  in  the  posterior  dorsal  part  of  the 
thigh,  using  for  this  work  the  handle  of  the  scalpel.     There 
should  be  found  the  white,  thread-like  Sciatic  Nerve.     Care- 
fully loosen  this  from  the  surrounding  tissues,  and  pass  one 
blade  of  a  pair  of  sharp  scissors  under  it.     Steady  the  hand, 
so  as  not  to  give  any  motion  to  the  suspended  frog  from  the 
act  of  cutting,  and,  while  closely  watching  the  foot,  cut  the 
nerve.     The  muscles  of  the  leg  shorten,  and  jerk  the  foot. 

3.  Again  pinch  the  toes  of  the  limb  whose  sciatic  nerve  is 
cut.     It  does  not  move.     Pinch  the  toes  of  the  other  foot ;  the 
leg  draws  up  as  before. 


38  REFLEX  ACTION. 

We  can  now  understand,  that  when  anything  touches  our 
toes  it  starts  what  is  called  a  Nerve  Current  or  Nerve  Impulse, 
which  runs  up  the  nerve  to  the  spinal  cord,  and  through  this 
to  the  brain.  If  the  brain  is  entire  and  awake,  we  have  what 
we  call  a  sensation  of  touch. 

The  feeling  seems  to  be  in  the  foot ;  but  there  is  no  feeling 
in  the  foot.  Without  the  brain  there  is  no  sensation.  If  the 
nerve  has  been  cut  no  sensation  is  produced,  because  the  nerve 
current  fails  to  reach  the  brain.  It  cannot  pass  the  break  in 
the  nerve  any  more  than  an  electric  current  can  pass  if  the 
wire  be  cut. 


—  Nerve-Cell 


Afferent   Fiber /  \     .  Efferent  Fiber 


Muscle 
Fig.  14.     Scheme  of  Reflex  Arc.     (After  Landois  &  Stirling.) 

But  our  frog  has  lost  his  brain ;  he  neither  feels  nor  wills 
to  do  anything.  How  is  it  that  he  draws  up  his  leg  when  his 
toes  are  pinched  ? 

4.  Run  a  wire  down  the  cavity  of  the  spinal  column.    This 
destroys  the  spinal  cord.     During  this  operation  it  will  be  seen 
that  the  muscles  of  nearly  the  whole  body  are  set  into  violent 
action.     This  is  because  nerve  impulses  are  produced  by  this 
irritation  of  the  motor  nerve-cells  of  the  cord  which  pass  out 
to  the  muscles,  causing  them  to  shorten. 

5.  Pinch  the  toes  again.     The  foot  is  no  longer  drawn  up. 
The  muscles  and  nerves  are  still  able  to  act,  as  is  seen  on 

pinching  the  end  of  the  nerve  still  connected  with  the  foot. 


REFLEX  ACTION. 


39 


Such  actions  as  the  struggling  of  the  chicken  whose  head 
has  been  cut  off,  and  of  the  brainless  frog  in  drawing  up  the 
foot  when  the  toes  are  pinched,  are  examples  of  Reflex  Action 
of  the  Spinal  Cord. 

When  the  toes  are  pinched,  the  nerve  current,  or  nerve 
impulse,  runs  up  the  nerve  to  the  spinal  cord.  The  gray  mat- 
ter in  the  central  part  of  the  spinal  cord  receives  the  message, 
and  sends  back  a  nerve  impulse  to  the  muscles  to  make  them 
shorten,  and  pull  the  foot  away. 


Afferent  Sensor  Fiber 
\ 


Dorsal   Root 


Muscle 


Motor  Fiber  \ 

Ventral   Root. 
Fig.  15.     Diagram  of  Reflex  Action  of  the  Spinal  Cord.    (After  Landois  &  Stirling.) 


The  sciatic  nerve  is  composed  of  many  fibers.  If  this  nerve- 
is  traced  outward,  it  is  found  to  be  continually  subdividing, 
and  sending  small  branches  to  the  muscles,  and  finally  in  the 
muscles  one  fine  nerve  fiber  goes  to  each  muscle  fiber.  Many 
fibers  go  on  past  the  muscles  to  the  skin.  We  can  feel  in  any 
part  of  the  skin,  and  we  can  tell  just  where  we  are  touched. 
These  fibers  from  the  skin,  then,  carry  nerve  impulses  inward, 
as  those  going  to  the  muscles  carry  impulses  outward. 

In  skinning  an  animal  we  see  many  bands  of  white  or 
transparent  tissues  connecting  the  skin  and  the  sheaths  of 


40  NEliVK 

the  underlying  muscles.  This  is  connective  tissue,  as  is  the 
sheath  of  the  muscle.  We  also  see  blood  tubes  running  out  to 
the  skin.  And  if  we  were  to  look  very  closely,  we  might  see 
fine  nerve  fibers  passing  from  the  skin  to  join  the  nerve  trunk 
in  the  legs  and  body.  To  skin  an  animal  alive,  then,  would 
mean  terrible  torture ;  because  all  these  nerve  fibers  would  be 
cut  or  torn  across,  and  every  injury  to  the  skin,  or  to  the 
nerve  fibers  running  inward  from  it,  sends  to  the  brain  nerve 
impulses  that,  in  the  normal,  live  animal,  arouse  sensations  of 
pain. 

We  have  already  seen  that  the  sciatic  nerve  is  made  up  of 
several  spinal  nerves,  and  that  each  of  the  nerves,  just  before 
entering  the  spinal  cord,  divides  into  two  roots,  one  entering 
the  cord  nearer  the  back,  the  dorsal  root ;  the  other  the  ven- 
tral root. 

Nerve  Roots  and  their  Functions.  —  Experiments  on 
the  lower  animals,  and  accidents  in  the  case  of  man,  show 
that  all  the  fibers  of  the  nerves  that  carry  currents  to  the 
muscles  pass  out  from  the  spinal  cord  into  the  ventral  root, 
and  that  all  the  fibers  that  carry  currents  inward  enter  the 
spinal  cord  through  the  dorsal  root.  Hence,  the  dorsal  root 
is  often  called  the  Sensory  root,  and  the  ventral  the  Motor  root. 
Since  the  dorsal  root  always  carries  currents  inward,  it  is  also 
called  the  Afferent  root,  while  the  ventral  root,  always  carry- 
ing currents  outward,  is  called  the  Efferent  root- 
Experiments  have  shown  that  if,  in  an  uninjured  animal, 
a  nerve,  or  more  properly  a  Nerve  Trunk  —  as  the  sciatic 
nerve,  —  be  stimulated,  for  instance,  by  a  suitable  electric 
shock,  two  effects  are  produced :  first,  notion  in  the  parts 
whose  muscles  are  supplied  by  the  nerve  ;  second,  sensation, 
which  is  referred  to  the  parts  of  the  akin  supplied  by  the 
branches  of  the  nerve. 

If,  instead  of  simply  stimulating  the  nerve,  the  nerve  is 


FUNCTIONS    OF  NERVE  HOOTS.  41 

severed,  the  same  two  effects  will  be  produced.  We  have 
seen  that  if  we  now  stimulate  the  end  of  the  nerve  still  con- 
nected with  the  limb,  we  get  action  of  the  muscles  in  that 
limb.  If  we  stimulate  the  end  of  the  nerve  connected  with 
the  body  a  sensation  will  be  produced,  and  this  sensation  will 
be  referred  to  the  parts  from  which  the  nerve  fibers  arise, 
probably  in  the  skin  of  the  limb. 

If  we  now  turn  to  the  roots  of  the  nerve,  and  try  similar 
experiments,  we  get  the  following  results :  Stimulating  the 
dorsal  root  causes  sensation  referred  to  some  outer  surface, 
and  no  other  effect  is  noticed.  Cutting  the  dorsal  root  also 
causes  sensation.  Stimulating  the  end  of  this  root  still  con- 
nected with  the  spinal  cord  causes  sensation ;  but  stimulating 
the  end  of  the  root  connected  with  the  nerve  gives  no  appre- 
ciable result. 

Stimulating  or  cutting  the  ventral  root  causes  motion  in 
the  parts  whose  muscles  are  supplied  by  fibers  from  this  root. 
After  severing  this  root,  if  the  end  connected  with  the  spinal 
cord  be  stimulated,  no  effect  is  noticed  ;  but  stimulating  the 
end  still  connected  with  the  nerve  is  followed  by  shortening 
of  the  muscles  supplied. 

Severing  all  the  spinal  nerves  destroys  all  power  of  sensa- 
tion and  voluntary  motion  in  all  parts  of  the  body  except  the 
head.  After  severing  all  the  dorsal  roots,  no  sensation  would 
be  produced  by  stimulating  any  part  of  the  body,  and  after 
severing  all  the  ventral  roots  no  act  of  the  will  can  cause  any 
of  the  muscles  of  the  body  to  act.  Severing  all  the  nerves,  or 
severing  all  the  roots,  cuts  off  all  communication  of  the  brain 
and  the  body,  and  so  far  as  motion  and  sensation  in  the  body 
generally  are  concerned,  has  the  same  effect  as  severing  the 
spinal  cord  below  the  head. 

The  parts  essential  to  reflex  action  of  the  spinal  cord 
are:  — 


42  ESSENTIALS   OF  REFLEX  ACTION. 

1.  A  sensitive  surface  (the  skin,  for  instance). 

2.  Afferent  nerve  fibers. 

3.  A  nerve  cell,  or  cells,  in  the  center  of  the  spinal  cord. 

4.  Efferent  nerve  fibers  (usually  many). 

5.  Working  organ,  as  muscle  or  gland. 

In  the  experiment  performed  the  steps  in  order  were :  — 

1.  Stimulation  of  the  nerve  endings  in  the  skin  of  the  toe. 

2.  Passage  of  a  nerve  impulse  up  the  afferent  fibers  to 
the  spinal  cord. 

3.  Reception  of  the  impulse  by  a  cell,  or  cells,  of  the  gray 
matter  in  the  cord. 

4.  Sending  back  nerve  impulses 

5.  Along  efferent  fibers  of  several  nerves,  to 

6.  Muscles  which  shorten  and  move  the  foot. 

It  is  important  that  we  understand  the  nature  of  reflex 
action,  for  very  many  of  the  processes  of  the  body  are  regu- 
lated by  it.  Not  only  the  more  manifest  motions,  such  as 
winking  when  anything  comes  quickly  toward  the  eye,  dodg- 
ing, jumping  when  suddenly  touched  by  anything  hot  or 
when  pricked  by  a  pin,  when  startled  by  a  sudden  loud  noise, 
making  a  quick  effort  to  regain  one's  balance  when  stumbling 
or  slipping ;  when  asleep,  brushing  away  a  fly  or  drawing  up 
the  foot  when  it  is  exposed  to  the  cold  —  not  only  are  all 
these  reflex  actions,  but  it  is  through  reflex  action  that  there 
are  brought  about  the  necessary  continual  adjustments  of  the 
essential  processes  of  life,  —  circulation,  respiration,  diges- 
tion. 

Cramp  is  a  spasmodic  shortening  of  the  muscles,  attended 
with  pain. 

Tetanus  (a  word  also  used  for  lock-jaw)  is  a  spasmodic 
and  continuous  shortening  of  the  muscles,  causing  rigidity  of 
the  parts  they  supply.  It  is  due  to  the  disordered  and  exces- 
sive stimulation  of  the  muscles  through  the  nerves. 


FUNCTIONS   OF  SPINAL   CORD.  43 

Functions  of  the  Spinal  Cord.  —  The  spinal  cord  has 
two  main  functions  :  — 

1.  Its   Conducting   Power,    by  means  of   the  white   fibers 
which  make  up  the  outer  part  of  the  cord.     These  fibers  may 
be  regarded  as  connecting  the  gray  matter  of  the  brain  with 
all  parts  of  the  body. 

2.  The  gray  matter  is  the  Center  of  the  Reflex  Actions  of 
the  cord. 

In  looking  at  the  cross-section  of  the  spinal  cord,  we  see 
that  the  dorsal  and  ventral  grooves  separate  it  into  right  and 
left  halves,  connected  by  a  comparatively  narrow  isthmus. 
In  this  narrow  part  are  fibers  connecting  the  two  halves. 
The  brain  also  consists  of  right  and  left  hemispheres  con- 
nected by  white  fibers.  Now,  the  gray  matter  of  the  outside 
of  the  cerebral  hemispheres  is  considered  the  chief  seat  of 
both  sensation  and  voluntary  motion. 

Further,  most  of  the  fibers  which  connect  this  gray  matter 
of  the  cerebral  convolutions,  cross  over  to  the  other  half  of 
the  spinal  cord  on  their  way  to  that  part  of  the  body  with 
which  they  connect.  Thus,  when  we  wish  to  move  the  right 
hand  the  action  starts  with  certain  changes  taking  place  in 
certain  cells  of  the  gray  matter  of  the  left  cerebral  hemi- 
sphere. Certain  fibers  extend  from  these  cells  down  to  the 
base  of  the  brain,  cross  in  the  spinal  bulb  to  the  other  half  of 
the  spinal  cord,  and  run  down  in  the  right  half  of  the  spinal 
cord  to  the  nerve  leading  to  the  muscles  to  be  controlled. 

Similarly,  the  sensory  nerves  cross  on  their  way  to  the 
brain,  only  they  are  believed  to  cross  soon  after  they  enter 
the  spinal  cord.  For  instance,  the  fingers  of  the  right  hand 
touch  an  object.  The  nerve  impulse  thus  started  runs  up 
the  afferent  fibers  of  the  nerve  of  the  arm.  As  it  reaches  the 
spinal  cord  it  passes  along  the  fibers  of  the  dorsal  root,  and 
enters  the  dorsal  part  of  the  cord.  It  then  crosses,  prob- 


44  JNU1BITIO\. 

ably  very  soon,  to  the  left  half  of  the  cord,  and  thence  up  on 
that  side  to  the  left  half  of  the  brain,  rousing  certain  cells  of 
the  cerebral  convolutions  to  an  activity  that  we  call  a  sensa- 
tion of  touch. 

Voluntary  Interference  with  Reflex  Actions.  —  We 
have  seen  that  the  jerking  of  the  hand  away  from  a  hot 
object  is  due  to  reflex  action  of  the  spinal  cord.  But  it  is 
possible,  by  act  of  .will,  to  prevent,  to  a  certain  extent,  the 
execution  of  reflex  acts.  One  might,  by  a  powerful  effort  of 
the  will,  keep  the  hand  on  an  object  that  is  hot  enough  to 
burn  the  skin.  But  we  frequently  see  examples  that  are  not 
so  extreme  as  this.  One  may  command  the  foot  to  remain 
quiet  when  it  is  tickled ;  he  may  keep  himself  from  scratch- 
ing a  part  of  the  skin  which  is  irritated ;  but  as  soon  as  the 
person  is  asleep  the  same  stimulations  would  be  followed  by 
the  reflex  actions  such  as  we  have  considered. 

In  these  cases  of  interference  it  is  understood  that  the 
brain  sends  a  nerve  impulse  down  to  the  centers  of  the 
reflex  action,  and  stops  or  diminishes  their  operation.  This 
retarding  influence  of  a  group  of  cells  is  called  Inhibition. 
It  is  not  always  due  to  voluntary  interference,  but  may  be 
due  to  reflex  interference,  as  we  may  see  later. 

The  Nature  of  a  Nervous  Impulse.  —  Of  the  nature  of 
a  nerve  impulse  we  know  but  little.  It  is  convenient  to  com- 
pare the  nervous  system,  with  its  conducting  fibers  and  cen- 
tral ganglia,  to  a  telegraph  system.  And  electricity  is  the 
most  convenient  stimulus  for  exciting  nerve  impulses.  Yet 
a  nerve  impulse  is  very  different  from  an  electric  current. 
A  nerve  fiber  is  a  poor  conductor  of  electricity.  An  electric 
current  may  travel  along  a  copper  wire  at  the  rate  of  between 
100,000  and  200,000  miles  a  second,  while  a  nerve  impulse  in 
a  motor  nerve  travels  only  170  feet  in  a  second. 

When  a  motor  fiber  is  stimulated  in  the  middle  of   its 


HARMONY  IN  MUSCLE  ACTION.  45 

course  we  observe  only  one  effect,  —  the  shortening  of  the 
muscle  at  its  lower  end.  But  there  is  every  reason  to  believe 
that  the  nerve  current,  or  impulse,  runs  along  the  nerve  in 
both  directions  from  its  starting-point.  But  while  the  action 
of  the  muscle  at  the  peripheral  extremity  manifests  the  exist- 
ence of  the  current,  there  is  nothing  at  the  central  extremity 
to  give  such  evidence. 

Similarly,  when  a  sensor  nerve  fiber  is  stimulated,  we  have 
a  sensation  in  the  brain  due  to  the  current  brought  by  the 
afferent  fiber,  and  which  we  refer  to  the  outer  ends  of  the 
nerve  fiber.  Probably  a  nerve  impulse  passed  from  the  point 
of  stimulation  to  the  outer  end  of  the  fiber ;  but  as  there  is 
nothing  at  the  outer  end  of  the  nerve  fiber  to  interpret  it,  we 
get  no  evidence  of  such  impulse  except  by  refined  physiologi- 
cal tests. 

Harmony  in  Muscle  Action.  —  Let  us  try  to  see  what 
takes  place  in  our  bodies  when  we  throw  a  stone  at  a  mark. 
Many  processes  are  involved,  such  as  seeing,  holding  the 
stone,  etc.  Let  us  confine  our  attention  chiefly  to  the  act  of 
throwing.  A  number  of  muscles  are  used.  Each  one  of  these 
must  shorten  in  the  right  way  and  at  the  right  time  or  the 
throw  will  not  be  accurate.  Each  muscle  shortens  under 
the  influence  of  a  nerve  impulse  started  by  the  brain  and 
brought  by  a  motor  nerve.  If  some  muscle  shortens  an  instant 
too  soon,  or  a  little  too  strongly,  the  stone  goes  to  one  side. 

When  we  listen  to  a  fine  performance  on  the  piano,  there 
are  certain  things  that  even  those  of  us  who  are  not  musical 
understand.  We  know  that  the  right  keys  must  be  struck ; 
that  each  must  be  struck  at  the  right  time,  with  the  right 
degree  of  force,  and  held  for  the  proper  length  of  time,  or  else 
we  have  a  harsh  jangle  of  sound  instead  of  sweet  harmony. 

What  the  player  is  to  the  instrument,  that  the  brayi  is  to 
the  body. 


46          DEPENDENCE  OF  NERVES  AND  MUSCLES. 

The  cells  of  the  brain  are  sending  messages  to  the  muscles. 
There  must  be  a  distinct  series  of  nerve  impulses  for  the  con- 
trol of  each  muscle.  The  impulses  must  be  in  the  proper 
sequence  and  of  the  right  degree  of  strength  to  make  each 
muscle  shorten  just  at  the  right  time,  with  the  right  force, 
for  the  right  length  of  time,  or  we  shall  have  muscular  con- 
fusion instead  of  orderly  and  accurate  movements. 

In  playing  a  game  of  tennis  the  brain  is  an  organist  with 
five  hundred  keys  before  him.  And  before  he  has  finished 
the  tune,  he  has  had  occasion  to  use  nearly  every  one  of 
them,  especially  if  the  player  is  not  only  dextrous  but  am- 
bidextrous. 

The  precision  and  rapidity  of  these  movements  are  most 
wonderful.  Imagine  an  organist  with  so  many  keys,  or  a  tel- 
egraph operator  sending  out  so  many  messages  over  so  many 
wires  in  so  brief  a  space  of  time,  and  getting  them  all  right. 
Yet  we  have  learned  all  this.  The  new-born  babe  has  little 
more  than  the  power  and  the  tendency  to  move.  Most  of  his 
acts  are  not  orderly.  He  gradually  learns  to  hold  up  his 
head,  to  sit,  to  grasp  objects,  to  walk,  to  throw,  and  execute 
all  the  co-ordinated  movements  that  we  now  discover  to  be 
primarily  under  the  management  of  the  two  Master  Tissues  (as 
Foster  calls  them),  Nervous  Tissue  and  Muscular  Tissue. 

Dependence  of  Nerves  and  Muscles.  —  It  may  have 
happened  to  you  that  after  sitting  long  in  one  position  you 
attempted  to  stand,  but  found  that  you  could  not  do  so.  One 
leg  failed  to  act  at  the  bidding  of  your  will.  Pressing  on  the 
foot  caused  little,  if  any,  sensation. 

Or,  perhaps,  you  may  have  awakened  in  the  night  and 
found  one  arm  numb  and  unable  to  move. 

When  the  foot  is  "  asleep  "  we  get  little  sensation  from  it ; 
we  hardly  know  whether  it  is  touching  the  floor  or  not.  Press- 
ing on  it  with  the  other  foot  causes  no  pain. 


DEPENDENCE   OF  NERVES  AND  MUSCLES.          47 

We  try  to  stand  when  the  foot  is  asleep,  but  we  are  unable 
to  do  so.  The  brain  starts  the  nerve  currents,  and  they  run 
along  the  nerve  as  far  as  the  compressed  part ;  here  they 
stop.  They  cannot  reach  the  muscles  of  the  leg  below. 
Hence  the  muscles  do  not  shorten,  and  we  do  not  rise,  no 
matter  how  strongly  we  will  to  do  so. 

Why  is  it  that  the  nerves  and  muscles  thus  sometimes  lose 
their  ability  to  perform  their  natural  activities  ? 

This  has  been  explained  by  saying  that  the  nerve  has  lost, 
for  the  time,  its  power  of  conducting  nerve  currents,  owing 
to  external  pressure.  But  is  it  not  possible  that  some  of  the 
effect  of  pressure  on  the  limb  is  indirect  rather  than  direct  ? 
That  something  beside  the  nerve  has  been  compressed,  and 
that  the  apparent  inability  of  the  nerve  to  convey  the  nerve 
impulse  is,  in  part,  a  secondary,  and  not  a  primary,  effect  ? 
What  process  in  the  limb  has  been  interfered  with  by  the 
pressure  due  to  the  position  in  which  one  has  been  sitting  or 
lying  ?  What  is  the  temperature  of  the  benumbed  limb  ? 

On  what  are  the  nerves  and  muscles  so  dependent  for  the 
maintenance  of  their  activity  ? 

READING.  —  Power  through  Repose,  Call ;   The  Technique  of 
Rest,  Brackett ;  Muscles  and  Nerves,  Rosenthal. 


CHAPTER   IV. 

CIRCULATION   OF  THE   BLOOD. 

The  Blood  and  its  Work.  —  If  the  supply  of  blood  to 
a  muscle  be  shut  off  by  tying  or  otherwise  compressing  the 
arteries  leading  to  it,  the  muscle  soon  loses  its  power  to  act. 
If  the  blood  supply  is  not  too  long  checked,  its  readmission 
will  restore  the  muscle  to  normal  condition.  If  the  blood  is 
wholly  shut  off,  say  from  one  of  the  lower  limbs,  there  would 
soon  be  loss,  not  only  of  muscular  power,  but  of  sensibility  as 
well. 

We  know  that  if  any  animal  is  bled  freely,  it  becomes 
weak,  then  unconscious,  and  soon  dies,  if  the  escape  of  blood 
is  not  stopped. 

We  observe  the  natural  difference  in  color  of  different  parts 
of  our  bodies ;  for  instance,  the  lips  and  cheeks.  We  often 
note  varying  color,  as  in  blushing  and  pallor. 

We  wish  to  understand  these  differences  and  changes ;  also 
to  know  what  to  do  in  case  of  fainting  or  bleeding  from 
wounds.  Our  comfort,  health,  and  often  life  itself,  may  de- 
pend on  our  knowledge  upon  this  subject.  We  may  prolong 
and  make  more  useful  our  own  lives  and  those  of  others  by 
knowing,  in  a  practical  way,  something  about  the  causes, 
prevention,  and  remedies  of  the  colds,  congestions,  and  inflam- 
mations to  which  we  are  subject. 

Nearly  every  part  of  the  body  bleeds  when  cut.  There  is 
no  bleeding  when  we  trim  the  nails  or  cut  the  hair,  and  the 
outer  skin  has  no  blood  in  it.  But  the  inner  skin,  and  almost 
every  tissue  within  it,  if  pierced,  even  by  the  finest  needle, 

48 


OBSERVATION   OF  CIRCULATION.  49 

yields  blood.  We  see  a  little  blood  oozing  from  the  surface  of 
a  fresh  steak  or  roast. 

What  kind  of  a  substance  is  the  blood  ?  Is  it  uniformly 
distributed  through  the  tissues,  like  water  soaked  up  into  a 
cloth,  or  is  it  in  distinct  cavities  ?  Why  is  it  so  essential  to 
life  ?  How  does  it  do  its  work  ? 

Let  us  seek  answers  to  these  questions. 


EXTERNAL   INDICATIONS    OP    THE    CIRCULATION   OP 
BLOOD    IN   THE    HUMAN   BODY. 

The  Heart-Beat  and  the  Pulse.  —  1.  The  heart-beat,  felt 
at  the  left  of  the  breast-bone. 

2.  The  pulse,  felt  at  the  wrist  and  at  various  parts  of  the 
body.  Perhaps  the  most  convenient  place  to  study  it  is  at 
the  temple.  Lay  the  forefinger  lightly  along  the  cheek  just  in 
front  of  the  ear.  Count  the  pulsations  for  a  minute. 

Let  one  or  two  pupils  who  are  quick  at  figures  step  to  the 
blackboard  and  put  down  the  number  of  pulsations  of  each 
pupil  as  they  are  called,  and  divide  by  the  number  thus  report- 
ing, to  get  the  average. 

1.  Let  all  in  the  class  count  the  pulse  while  sitting.    Prob- 
ably it  will  be  best  to  discard  the  first  trial,  as  there  are  likely 
to  be  several  failures  from  one  cause  or  another.     Then,  too, 
there  is  usually  a  slight  excitement  at  the  beginning  of  a 
wholly  new  experiment.     Get  the  average  of  the  class. 

2.  Find  the  pulse  while  sitting;  rise  quickly,  and  imme- 
diately begin  to  count  the  pulse.     Compare  with  the  pulse  as 
taken  while  sitting. 

3.  Again  find  the  pulse  after  sitting  quietly  for  some  time ; 
rise  quickly,  begin  counting  immediately,  and  note  the  num- 
ber at  the  end  of  a  half-minute,  but  count  on  continuously  to 


50  OBSERVATION  OF  CIRCULATION. 

the  end  of  the  minute.     Compare  the  number  of  pulsations 
in  the  first  half-minute  with  that  in  the  second  half. 

4.  Stand  and  take  active  exercise  for  a  few  minutes,  as  if 
with  dumbbells.     Immediately  count  the  pulse. 

5.  At  home,  count  the  pulse  while  lying  on  a  lounge,  after 
remaining  in  that  position  for  half  an  hour. 

6.  Compare  the  pulse  before  and  after  meals. 

7.  With  the  thumb  and  finger  lightly  clasp  the  windpipe, 
well  back.     The  pulse  in  the  Carotid  arteries  will  be  felt. 

Let  all  the  pupils  in  the  class  stand.  Let  one  arm  hang 
freely  by  the  side.  Hold  the  other  arm  straight  up  as  far  as 
the  clothing  will  readily  permit.  Observe :  — 

1.  The  difference  in  the  color  of  the  two  hands. 

2.  The  difference  in  fulness,  both  in  the  feeling  of  ful- 
ness and  in  the  prominence  of  the  veins. 

3.  The  difference  in  temperature ;  place  the  backs  of  the 
hands  against  the  cheeks. 

The  position  largely  determines  the  amount  of  blood  in 
the  hand,  and  the  amount  of  blood  determines  the  tempera- 
ture, the  size,  and  the  color. 

With  the  forefinger  stroke  one  of  the  veins  on  the  hand  or 
wrist  toward  the  tips  of  the  fingers.  The  vein  swells  out. 
The  blood  meets  resistance  in  the  valves  of  the  vein.  Their 
location  may  be  determined  by  their  bulging  out  during  the 
experiment. 

Stroke  a  vein  toward  the  body,  and  the  blood  is  pushed 
along  without  resistance. 

Let  the  left  hand  hang  by  the  side.  Note  the  large  vein 
along  the  thumb  side  of  the  wrist.  Place  the  tip  of  the 
second  finger  on  this  vein  just  above  the  base  of  the  thumb. 
Now,  while  pressing  firmly  with  the  tip  of  the  second  finger, 
let  the  forefinger,  with  moderate  pressure,  stroke  the  vein  up 
the  wrist.  It  may  be  seen  that  the  blood  is  pushed  on  freely, 


BLOOD   CORPUSCLES.  51 

but  comes  back  only  part  way.  It  stops  where  it  reaches  the 
valves,  filling  the  vein  full  to  this  point,  but  leaving  it  col- 
lapsed beyond,  as  shown  by  the  groove.  Remove  the  second 
finger,  and  the  vein  immediately  fills  from  the  side  nearer  the 
tip  of  the  fingers. 

These  experiments  show  that  the  blood  in  the  veins  moves 
freely  toward  the  body,  but  cannot  flow  outward  to  the 
extremities. 

With  the  finger-tips  press  on  the  back  of  the  hand.  Note 
the  temporary  white  spot  caused  by  the  pressure. 

Observe  the  color  of  the  finger-nails  in  the  closed  (but  not 
clinched)  hand.  Now  straighten  the  fingers  as  far  back  as 
possible,  and  again  note  the  color  of  the  nails.  Press  the 
nail  on  its  surface,  ends,  sides,  and  note  the  changes  in  color. 

A  Drop  of  Frog's  Blood.  —  Kill  a  frog  as  directed  on 
page  13.  If  blood  enough  is  not  obtained  from  the  wound 
already  made,  open  the  body  cavity  and  cut  across  the  heart. 

Place  a  small  drop  of  blood  on  each  of  several  slides  and 
quickly  cover  with  coverslips. 

First  examine  with  a  low  power,  one  inch,  or  half-inch 
objective.  Then  with  a  one-fifth  inch  objective.  There  wilJ 
be  seen :  — 

1.  The   Colored  Corpuscles.     They  are  yellowish  pink  in 
color,  elliptical  in  shape.     Some  of  them,  seen  edgewise,  will 
be  seen  to  be  flattened,  with  a  bulging  center.     This  bulge  is 
caused  by  the  Nucleus. 

2.  The  Colorless  Corpuscles,  few  in  number  compared  with 
the   colored  corpuscles,  much  smaller,  ordinarily  circular  in 
outline,  because  they  are  usually  spherical.     They  are  almost 
always  dotted  in  appearance.     If  watched  closely  for  some 
time  they  may  be  seen  to  change  their  shape,  like  the  Ameba. 
Watch  these  changes.     Make  drawings  of  the  outline  at  in- 
tervals of  ten  seconds. 


52 


'O  +  n  KL\    OF  BLOOD. 


The  clear  spaces  between  the  corpuscles  is  filled  with  the 
liquid  part  of  the  blood,  called  the  Plasma. 

Our  blood  is  very  much  like  that  of  the  frog,  as  we  shall 
see  a  little  later. 


r.  PIGMENT 

CELLS 


ARTERY 
Fig.  16.    Part  of  Frog's  Web  (low  magnifying  power). 


CAPILLARY  CIRCULATION. 


53 


The  Circulation  of  Blood  in  the  Web  of  a  Frog's 
Foot.  —  For  this  get  a  frog  with  a  pale  web.  Take  a  piece 
of  shingle  six  inches  long  and  three  inches  wide.  Cut  a 
round  hole,  half  an  inch  in  diameter,  near  one  end  of  it. 


Walls  of  Capillaries 


Tissues  of  Web 


Fig.  17.     Part  of  Frog's  Web  (highly  magnified). 


BLOOD   CAPILLARIES. 


Wrap  the  frog  in  a  wet  cloth,  with  one  leg  projecting,  and 
tie  it,  thus  wrapped,  to  the  shingle.  Tie  threads  around  two 
of  the  toes,  and  stretch  the  web,  but  not  too  tightly,  over  the 
hole.  Place  the  shingle  firmly  on  the  stage  of  a  microscope. 
Examine  first  with  a  low  power.  The  large  tubes  which  grow 
smaller  by  subdivision  are  Arteries.  The  large  tubes  which 
are  formed  by  the  union  of  smaller  ones  are  the  Veins.  The 
finer  tubes,  forming  a  network  in  every  direction,  are  the 
Capillaries.  They  receive  the  blood 
from  the  arteries,  and  pass  it  on  to 
the  veins. 

Put  on  a  higher  power,  a  one-fifth 
or  one-sixth  objective.  It  may  now 
be  seen  that  the  colored  corpuscles 
float  more  in  the  center  of  the 
stream,  and  with  a  steady  motion, 
while  the  colorless  corpuscles  keep 
close  to  the  walls  of  the  capillary, 
and  seem  to  adhere  to  them,  ad- 
vancing writh  a  hesitant  motion, 
seeming  to  roll  along  against  the 
wall  of  the  capillary. 

Close  your  eyes  for  a  moment, 
and  reflect  that  in  all  the  active 

tissues  of  your  body  —  for  example,  the  muscles,  brain,  and 
digestive  organs  —  there  is  a  similar  network  of  fine  tubes 
with  a  current  of  blood  running  through  them.  The  current 
is  not  so  rapid  as  it  seems,  for  the  microscope  magnifies  the 
rate  of  flow  as  well  as  the  size  of  the  corpuscles.  The  blood 
really  is  moving  slowly  in  the  capillaries ;  and  it  is  very  im- 
portant that  it  should  be  so,  for  in  the  capillaries  the  work 
of  the  blood  is  done.  Part  of  the  liquid  of  the  blood  soaks 
through  the  thin  walls  of  the  capillaries,  and  nourishes  the 


Fig.  18.    Capillary  Blood  Tubes 
of  Muscle. 


DISSECTION   OF  HEART  AND  LUNGS.  55 

surrounding  tissues.  All  the  other  parts  of  the  circulatory 
system  exist  for  the  purpose  of  sending  a  continuous,  slow, 
and  steady  stream  of  blood  through  the  capillaries. 

INTERNAL  PROOFS   OF   THE    CIRCULATION    OF    THE    BLOOD. 

Heart  and  Lungs  of  a  Pig.  —  Get  the  butcher  to  save 
the  heart  and  lungs  entire  (the  " pluck"),  being  careful  not 
to  cut  the  lungs  or  the  heart  case.  If  a  considerable  number 
are  needed  it  is  better  not  to  depend  on  local  butchers,  but 
to  send  to  a  large  slaughtering-house  in  the  nearest  city.  The 
"  plucks  "  should  be  thoroughly  cooled  before  being  shipped. 

1.  Hold  up  the  mass  by  the  windpipe,  with  the  heart  away 
from  you.     The  end  now  uppermost  is  the  anterior  end,  that 
below  is  the  posterior  end  ;  the  lung  to  your  right  is  the  right 
lung ;  the  one  to  your  left  is  the  left  lung  ;  the  surface  near- 
est you  is  the  dorsal  surface,  and  that  opposite  is  the  ventral 
surface. 

2.  Observe  the  windpipe,  or  Trachea,  with  the  stiff  rings  of 
gristle,  or  Cartilage.     The  thick  part  of  the  anterior  end  is  the 
Larynx. 

3.  Running  along  the  dorsal  surface  of  the  windpipe  is  a 
soft  red  tube,  the  Gullet,-  or  Esophagus.     At  about  the  middle 
of  the  windpipe  separate  the  gullet  and  windpipe  for  three 
or  four  inches.     Note  that  next  to  the  gullet  the  windpipe  is 
soft  and  yielding  where  the  gaps  of  the  C-shaped  cartilages 
are  filled  with  muscular  and  elastic  tissue.     Make  a  slit  two 
inches  long    in  this  soft  membrane. 

4.  Innate   the  lungs  as   follows:  Take  a  wooden  faucet, 
slip  the  small  end  of  the  faucet  into  the  slit  just  made  in  the 
windpipe,  and  hold  or  tie  firmly,  but  do  not  cut  off  either  gul- 
let or  windpipe.     Inflate  through  the  spout,  then  shut  off  the 
air  ;  if  the  lungs  have  not  been  punctured  they  should  now 


56  DISSECTION  OF  LUNG. 

remain  distended.  In  holding  up  the  lungs,  take  hold  of  the 
windpipe  above  where  it  is  tied,  and  not  of  the  faucet.  Note 
(a)  the  conical  shape  of  the  whole  ;  compare  this  with  the 
chest  cavity,  as  shown  in  a  skeleton ;  (&)  how  the  lungs  nearly 
surround  the  heart ;  (c)  the  concave  posterior  surface  of  the 
lungs  where  they  fitted  the  convex  anterior  surface  of  the  dia- 
phragm ;  (d)  the  groove  between  the  dorsal  surfaces  of  the 
lungs  in  which  the  spinal  column  fitted  ;  (e)  the  smooth,  un- 
divided dorsal  surface  of  the  lungs,  and  their  division  ven- 
trally  into  Lobes ;  (/)  the  relative  lengths  of  the  dorsal  and 
ventral  surfaces  of  the  lungs.  The  anterior  end  of  the  lung  is 
the  Apex;  the  posterior  end  is  the  Base.  Open  the  valve  of 
the  faucet.  What  makes  the  air  go  out  ?  Again  inflate.  Does 
it  require  effort  to  do  so  ?  Why  ?  Cut  off  the  end  of  one 
lobe  and  again  inflate.  Does  the  air  escape  ?  Throw  a  piece 
of  lung  on  water.  Pinch  a  piece  of  lung,  holding  it  near  the 
ear.  The  smooth,  moist,  glistening  membrane  covering  the 
lung  is  the  Pleura. 

5.  Observe  a  large  whitish  or  yellowish  tube  running  in 
the  groove  between  the  dorsal  surfaces  of  the  two  lungs.     It 
is  usually  covered  with  fat,  and  if  it  has  been  cut  off  short 
its  open  end  is  easily  seen   near  the  windpipe.     This  is  the 
main  artery,  the  Aorta.     Take  hold  of  its  free  end,  and  sepa- 
rate it  from  its  attachment  to  the  other  tissues,  cutting  close 
to  it  with  the  scissors,  so  far  as  where  it  arches  over  the  root 
of  the  left  lung.     Now  turn  the  free  end  forward. 

6.  Find  where  the  gullet  is  cut  off  posteriorly ;  slit  it  open 
for  an  inch  or  two,  and  note  its  whitish  lining,  the  Mucous 
Coat.     The  thick  red  coat  is  the  Muscular  Coat ;  try  to  dis- 
tinguish an  inner  layer  of  circularly  arranged  muscle  fibers 
and  an  outer  longitudinal  layer.     Beginning  posteriorly,  sep- 
arate the  gullet  from  the  windpipe,  cut  off  the  windpipe  about 
the  middle,  and  entirely  remove  the  gullet  and  larynx. 


HEART  —  PERICARDIUM.  57 

7.  Examine  the  windpipe  ;  insert  a  finger,  and  stretch  it  ,• 
note  its  C-shaped  cartilages.    Its  lining  is  a  Mucous  Membrane. 

8.  Lay  the  heart  and  lungs  on  their  ventral  surface,  with 
the  posterior  end  nearer  you.     Using  the  handle  of  the  scal- 
pel as  a  chisel,  clear  away  any  tissue  covering  the  windpipe, 
and  trace  it  to  the  lungs  ;  its  branches  are  the  Bronchi.     How 
many  bronchi  are  there  ?     Here  are  often  found  small,  oval, 
brownish  masses,  the  Lymphatic  Glands,  imbedded  in  connective 
tissues.     Scrape  these  loose  with  the  scalpel  handle. 

9.  Lay  the  lungs  on  their  dorsal  surface,  with  the  anterior 
ends  toward  you.     Note  how  easily  the  heart  may  be  moved 
about  in  its  case,  the  Pericardium.     Slit  the  pericardium  along 
its  ventral  side,  and  note  the  smoothness  of  its  lining  and  of 
the  surface  of  the  heart.     Observe  the  Pericardial  Fluid. 

10.  Carefully  compare    the  right  and   left   sides    of   the 
heart.     Running  obliquely  across  the  surface  of  the  heart  is 
a  groove  in  which  are  blood  tubes,  often  covered  with  fat. 
The  part  at  the  right  of  the  groove  is  the  Right  Ventricle ;  at 
the  left  is  the  Left  Ventricle. 

11.  At  the  base  (anterior  end)  of  the  heart  on  each  side 
are  the  right  and  left  Auricles. 

12.  Tip  up  and  toward  you  the  apex  of  the  heart.     Com- 
pare its  width  and  thickness  ;  compare  the  ventral  and  dorsal 
surfaces  as  to  length,  convexity,  etc.     Compare  its  width  and 
thickness ;    press  the  two  ventricles,   and  compare  them  in 
firmness. 

•13.  Turn  the  heart  to  the  left,  and  examine  the  right  auri- 
cle; find  a  large,  flabby,  red-lined  tube  entering  its  anterior 
surface,  the  Precaval  Vein.  Prick  a  small  hole  in  it  near  the 
pericardium  and  insert  the  blowpipe ;  hold  firmly  around  the 
opening  and  inflate  the  right  auricle  ;  the  Postcaval  Vein  should 
now  be  discovered  entering  the  auricle  from  the  posterioi 


58  PULMONARY  BLOOD-TUBES. 

region.     Look  for  it  outside,  and  on  the  dorsal  side  of  the 
pericardium,   where  it  runs  anteriorly  from  the  diaphragm. 

14.  Turn  the  heart  to  the  right,  and  observe  a  large,  light- 
colored  tube  arising  from  the  base  of  the  right  ventricle  be- 
tween the  two  auricles ;  this  is  the  Pulmonary  Artery.     Again 
turn  the  heart  to  the  left,  and  raise  the  right  auricle ;  find  the 
Aorta  arising  from  the  center  of  the  base  of  the  heart.     Care- 
fully separate  the  aorta  from  the  pulmonary  artery,  and  trace 
the  aorta  as  it  arches  over  the  left  bronchus,  and  runs  down 
between  the  two  lungs  by  the  side  of  the  gullet.     Clear  away 
any  fat  or  other  tissue  adhering  to  it. 

15.  From  the  arch  of  the  aorta  arise  the  branches  running 
to  the  head  and  forelimbs. 

16.  In  the  same  way  trace  and  clear  the  pulmonary  artery. 

17.  When    the   fork  of   the   pulmonary  artery  has    been 
reached,  lay  the  heart  and  lungs   on  their  ventral  surfaces, 
with  the  posterior  end  toward  you ;  turn  the  windpipe  back 
toward  you,  and  with  the  scalpel  handle  trace  the  branches  of 
the  pulmonary  artery  into  the  lungs.     Cut  them  off  close  to 
the  lungs. 

18.  Keeping  the  parts  in  the  same  position,  trace  the  Pul- 
monary Veins.     These  are  to  be  found  on  the  ventral  side  of 
the  bronchi ;  their  general  outlines  may  be  shown  by  inflating 
as  follows  :  Cut  off  the  first  branch  of  the  aorta  as  close  as 
possible  to  the  arch.     Insert  one  blade  of  the  scissors  in  this 
opening,  pointing  away  from  the  heart,  and  make  a  slit  two 
inches  long.     Insert  a  cork  toward  the  heart.     It  should  fit 
snugly,  so  that  air  may  not  escape.     For  a  pig's  heart  a  cork 
about  three-fourths  of  an  inch  in  diameter  at  its  larger  end  is 
about  right.     Make  a  very  small  hole  in  the  tip  of  the  left 
auricle,  insert  the  blowpipe,   holding  firmly  around  it,  and 
inflate.      This  should  distend  the   left  auricle  and  the  pul- 
monary veins.     With  the  handle  of  the  scalpel  scrape  away 


I 


STRUCTURE   OF  THE  HEART.  59 

fat  or  connective  tissue  that  covers  them,  and  trace  them,  to 
the  left  auricle.  How  many  are  there  ?  Cut  off  the  left 
bronchus  close  to  the  lung,  and  turn  the  windpipe  to  the  right. 
Clear  the  pulmonary  veins  from  any  tissue  that  lies  under 
them.  Turn  now  to  the  ventral  surface  of  the  heart ;  lift  the 
ventral  margin  of  the  flap  of  the  left  auricle,  and  with  scissors 
cut  into  the  left  auricle  in  the  groove  between  the  left  auricle 
and  the  left  ventricle.  Make  a  slit  an  inch  long,  following 
the  groove.  Pass  a  probe  through  the  opening,  then  directly 
across  the  cavity  of  the  auricle,  to  the  dorsal  wall  of  the 
auricle.  Here  are  the  entrances  of  the  veins  from  the  right 
and  left  lungs.  Use  the  finger  as  a  probe,  enlarging  the  open- 
ing a  little  if  necessary.  Cut  off  the  pulmonary  veins  near 
the  lungs,  cautiously  avoiding  other  blood  tubes ;  trim  away 
the  pericardium.  If  the  preceding  work  is  interrupted  at 
about  this  point,  wrap  the  heart  first  in  wet,  then  in  dry 
paper ;  write  your  name  upon  the  wrapper,  and  keep  the  heart 
in  a  cool  place  for  later  study. 

19.  With  the  scissors  slit  down  one  bronchus  through  the 
lung,  noting  its  branches.  Follow  the  outside  of  another 
bronchus,  tearing  away  the  lung  tissue  with  the  scalpel  handle. 

Structure  and  Action  of  the  Heart.  —  1.  Briefly  re- 
view :  precaval  vein ;  postcaval  vein ;  right  auricle ;  right 
ventricle  ;  pulmonary  artery  ;  pulmonary  veins  ;  left  auricle  ; 
left  ventricle ;  aorta.  Hold  the  heart  suspended  by  the  end 
of  the  aorta,  and  dance  it  up  and  down  to  show  the  elasticity 
of  the  aorta.  Cut  off  the  aorta  where  the  slit  was  made  at 
the  arch,  and  feel  the  inner  surface. 

2.  Eun  a  probe  into  the  precaval  vein,  through  the  right 
auricle,  and  out  of  the  postcaval  vein.  Cut  along  the  upper 
side  of  the  probe,  and  explore  the  cavity  of  the  right  auricle. 
Feel  the  inside  of  the  auricle  and  veins.  Observe  that  the 
cavity  of  the  auricle  extends  farther  into  the  heart  than  the 


60  DISSECTION  OF  Til  K   II  KM  IT. 

notch  between  the  auricle  and  ventricle.  At  the  extreme  left 
of  the  right  auricle  is  the  mouth  of  the  Cardiac  (coronary) 
Vein,  which,  running  around  between  the  left  auricle  and  left 
ventricle,  brings  blood  from  the  ventral  wall  of  the  heart. 
Near  the  mouth  of  this  vein  also  empty  the  veins  seen  in 
the  dorsal  wall  of  the  heart.  Pick  out  any  clots  that  may 
be  found.  Slit  the  anterior  wall  of  the  auricle,  being  careful 
not  to  cross  the  groove  between  the  auricle  and  ventricle, 
and  note  the  muscular  columns  within  the  appendage  of  the 
auricle. 

3.  Cut  away  the   whole  of   the  appendage  of   the  right 
auricle.     Remember  that  the  pulmonary  veins  from  the  right 
lung  run  very  close  to  the  right  auricle,  and  be  careful  not  to 
cut  into  them.     Pin  down  the  flap  of  the  left  auricle,  so  that 
water  may  not  enter  the  left  half  of  the  heart  in  the  next 
experiment.     Hold  the  heart  in  the  left  hand,  with  the  ven- 
tral surface  in  the  palm,  and  the  tips  of  the  fingers  against 
the  right  ventricle.     Hold  the  heart  under  a  faucet,  or  pour 
from  a  pitcher,  and  let  the  water  run  first  gently,  then  strongly, 
through  the  right  auricle  into  the  right  ventricle.     Watch  the 
Tricuspid  Valves  as  they  float  up  and  separate  the  auricle  from 
the  ventricle.     Empty  the  heart  and  fill  it  again,  and  as  soon 
as  the  valves  rise,  press  with  the  fingers  on  the  outside  of  the 
ventricle.     What  effect  has  this  pressure  ?     Let  the  nozzle  of 
the  faucet  project  down  between  the  valves,  and  again  turn 
on  the  water.     Where  does  the  water  escape  ? 

4.  Empty  the  heart  and  examine  the  valves.     They  will 
be  found  lying  close  against  the  walls  of  the  ventricle.     Note 
the  white  cords,  Chordae  Tendineae.  attached  to  the  valves. 

5.  Push  the  finger  past  these  valves  to  the  very  bottom  of 
the  ventricle ;  from  the  outside  cut  through  the  wall  of  the 
ventricle  at  this  point,  and  cautiously  cut  upwards  in  both 
directions  along  the  border  of  the  ventricle.     Raise  the  outer 


VALVES   OF  THE  HEART.  61 

wall  of  the  ventricle,  and  study  the  valves  more  thoroughly ; 
with  the  scalpel  handle  raise  them  from  the  walls  of  the  ven- 
tricle. How  many  flaps  are  there  ?  How  are  they  arranged  ? 
The  conical  elevations  of  the  muscle  to  which  the  chordce  ten- 
dinece  are  attached  are  the  Papillary  Muscles.  How  are  the 
valves  held  in  place  ?  How  are  they  acted  on,  and  how  do 
they  act  ? 

6.  Find  the  connection  between  the  right  ventricle   and 
the  pulmonary  artery;  pass  a  probe  up  into  the  pulmonary 
artery.     Cut  away  enough  of  the  wall  of  the  ventricle  to  show 
the  beginning  of  the  artery.     Cut  off  the  pulmonary  artery 
just  before  it  forks  to  the  two  lungs;  slip  over  the  faucet  the 
end  of  the  artery  connected  with  the  heart,  and  turn  on  a 
little  water.     Watch  closely  the  base  of  the  artery ;  turn  on 
more  water,  and  look  from  below  at  the  base  of  the  artery,  to 
see  the  filling  of  the  pocket-like  Semilunar  Valves.     Note  their 
number,  shape,  and  arrangement.     What  is  the  effect  of  the 
stream  of  water  upon  them,  and  what  is  their  effect  upon 
the  stream  of  water? 

7.  Examine  the  left  auricle,  and  find  where  the  pulmonary 
veins  enter  it.    Cut  away  the  lobe  of  the  left  auricle;  examine 
its  inner   surface,  and  find   the   openings  of  the   pulmonary 
veins.     Hold  under  a  faucet,  and  prove  the  action  of   the 
Mitral  Valve,  between  the  left  auricle  and  the  left  ventricle. 
Insert  the  nozzle  of  the  faucet  between  the  valves,  and  again 
turn  on  the  water.     Where  does  it  escape  ?     Cut  off  the  aorta 
half  an  inch  from  its  base,  and  repeat  the  last  experiment 
with  the  water,  meanwhile  closely  watching  the  semilunar 
valves  of  the  aorta. 

8.  Above  the  pockets  of  the  semilunar  valves  look  for  the 
openings  of  the  Cardiac  (coronary)  Arteries,  which  supply  the 
walls  of  the  heart.     Probe  them.     How  many  are  there  ? 

9.  Pass  the  handle  of  the  scalpel  between  the  semilunar 


62  ACTION  OF  THE  II K ART. 

valves  of  the  aorta  into  the  left  ventricle  ;  it  passes  back  of 
one  flap  of  the  mitral  valve. 

10.  Cut  open  the  left  ventricle.     Note  the  strong  muscu- 
lar columns,  the  strong  papillary  muscles  ;   the  mitral  valve, 
though  ending  in  two  main  flaps  below,  is  continuous  at  the 
top.     Compare  the  walls  of  the  right  with  those  of  the  left 
ventricle.     Why  this  difference  ?     Note  the  partition  between 
the  ventricles.     Is  there  any  direct  communication  between 
the  right  and  left  halves  of  the  heart  ? 

11.  Slit  open   the  aorta   between   two  of   the   semilunar 
valves,  and  study  the  valves  more  closely.     In  the  middle  of 
the  free  border  of  each  valve  note  the  little  thickened  point, 
the  Corpus  Arantii.     When  the  valves  close,  these  three  little 
points  fill  up  a  small  three-cornered  opening  that  would  other- 
wise be  left  between  the  valves.     Again  examine  the  cardiac 
arteries. 

12.  In  another  heart,  carefully  cut  around  the  base  of  the 
pulmonary  artery,  tie  its  outer  end  tightly  over  the  end  of  a 
glass  tube  or  spool,  and  show  the  action  of  the  semilunar 
valves,  by  blowing  suddenly  and  forcibly  into  the  tube.     To 
keep  the  glass  tube  from  slipping  out,  slip  an  inch  of  thick 
rubber  tubing  on  the  end  of  the  glass  tube,  so  that  the  rubber 
tube  is  even  with  the  end   of  the  glass  tube.      The   valves 
work   better  when   moist   and   flexible ;    therefore    keep  the 
preparation  standing  in  a  jar  of  water  until  it  is  to  be  used. 
Slit  open  the  artery,  and  study  the  valves. 

13.  Longitudinal  and  cross  sections  of  a  frozen  heart  are 
instructive. 

Demonstration  of  the  Action  of  the  Heart.  —  Get  the 
heart  and  lungs  entire.  Dissect  out  the  aorta  as  before.  Clear 
the  pulmonary  artery,  and  cut  off  both  branches  close  to  the 
lungs.  Carefully  trim  away  the  pericardium,  and  clean  the 
precaval  and  postcaval  veins.  Turn  the  heart  back,  and  find 


ACTION   OF  THE  HEART.  63 

one  of  the  larger  pulmonary  veins  ;  cut  a  hole  in  it  near  the 
lung,  and  slip  a  glass  tube  into  it  toward  the  heart.  This  tube 
should  have  a  groove,  made  by  drawing  it  out  in  the  flame. 
Another,  and  perhaps  easier,  way  to  keep  the  glass  tube  from 
slipping  out,  is  to  slip  over  the  end  of  the  tube  a  piece  of  rub- 
ber tube  an  inch  or  two  long;  but  it  should  not  project  beyond 
the  end  of  the  glass  tube.  If  this  fits  snugly,  it  will  not  slip 
on  the  glass  tube,  and  the  blood  tubes  will  hold  firmly  when 
tied  over  the  rubber.  It  is  much  better  to  tie  the  tube  into  the 
pulmonary  vein  before  the  vein  is  cut  off;  otherwise  there  will 
be  difficulty  on  account  of  the  shortness  of  the  pulmonary 
vein.  Tie  the  tube  firmly  in,  and  ligature  the  other  pulmonary 
veins  without  stopping  to  trace  them.  Tie  all  connections 
with  the  heart  now  remaining,  and  cut  beyond  the  ligatures. 
Get  a  retort  stand  and  two  large  glass  funnels,  or  have  made 
a  more  convenient  piece  of  apparatus  (as  shown  in  Fig.  19), 
consisting  of  a  sheet-iron  pan  eighteen  inches  square  and  two 
inches  deep,  with  a  fixed  bail  handle  twenty  inches  high,  made 
of  iron  rod  of  the  size  of  a  retort-stand  rod.  Attach  retort 
rings  and  clamps  to  the  rod,  as  shown  in  the  figure.  This 
whole  apparatus,  with  the  heart  attached  according  to  the 
directions  given,  can  easily  be  carried,  and  any  overflow  of 
liquids  will  be  caught  by  the  pan.  Place  the  funnels  in  the 
rings.  Lay  the  heart,  now  wholly  severed  from  the  lungs,  on 
its  ventral  surface.  Connect  one  funnel  by  rubber  and  glass 
tubing,  with  the  left  auricle  by  the  tube  already  in  the  pul- 
monary vein ;  connect  the  other  funnel  with  the  right  auricle, 
through  the  precaval  vein ;  ligature  the  postcaval  vein.  Lay 
the  heart  in  a  basin,  and  pour  water  into  the  funnels ;  hold 
the  heart  with  the  two  hands,  and  compress  it,  repeatedly 
adding  water.  In  this  way  the  clotted  blood  usually  present 
in  the  right  ventricle  may  be  washed  out.  If  this  remain, 
it  may  interfere  with  later  experiment.  Connect  the  aorta 


64 


ACTION    OF  Till':   HEART. 


with  the  funnel  which  leads  to  the  right  auricle  by  means 
of  a  glass  tube  which  bends  over  the  edge  of  the  funnel,  thus 
holding  itself  in  place  by  the  hook,  or  held  above  by  a  clamp 
or  ring,  and  emptying  into  this  funnel  any  liquid  which 
escapes  from  the  tube. 

In  like  manner  have  a  bent  glass  tube,  from  the  pulmonary 


Capillaries 
of  the  Lungs 


Capillaries 
of  the  Body 


Fig.  19.     Demonstration  of  the  Action  of  the  Heart  (Heart  Diagrammatic.) 

artery,  held  by  a  clamp  above  the  funnel  leading  to  the  left 
auricle. 

If  possible,  let  the  heart  soak  in  water  over  night  before 
showing  it  to  the  class.  This  will  loosen  the  clots,  and  make 
the  valves  more  flexible. 

Pour  water  into  one  of  the  funnels,  and  compress  the  heart 
to  imitate  its  natural  contraction;  observe  where  the  liquid 


INJECTION   OF  THE  ARTERIES.  65 

next  appears  ;  add  more  water,  and  follow  it  around  to  its 
starting-point.  A  little  ink  may  be  poured  into  one  of  the 
funnels,  and  traced  around,  as  the  heart  is  worked,  to  its 
starting-point. 

That  there  is  no  direct  connection  between  the  two  halves 
of  the  heart  may  be  shown  by  letting  the  liquid  from  each 
artery  empty  into  the  funnel  connected  with  the  auricle  of  the 
same  side  of  the  heart.  Different-colored  liquids  may  be  used 
in  the  two  funnels. 

In  order  to  illustrate  more  fully  how  the  heart  is  com- 
posed of  two  pumps  fastened  together,  and  each  pumping  its 
own  stream,  but  worked  by  the  same  power,  try  the  fol- 
lowing :  — 

Take  the  two  funnels  supported  as  in  the  preceding  experi- 
ment ;  connect  each  funnel  with  the  supply  tube  of  a  common 
bulb  syringe ;  connect  the  delivery  tubes  with  the  bent  tubes 
used  with  the  heart. 

1.  Let  each  bent  tube  empty  into  the  funnel  from  which 
it  gets  its  supply.     There  are  now  two  distinct  circuits. 

2.  Now  cross  the  delivery  tubes  so  that  each  discharges 
into  the  funnel  from  which  the  other  gets  its  supply.     Now, 
on  working  the  bulbs,  we  have  a  circuit  like  a  figure  8,  really 
one  circuit,  but  the  two  streams  cross  each  other. 

3.  Again,  place  the  two  bulbs  side  by  side,  and  work  the 
two  with  one  hand. 

4.  Wrap  a  cloth  around  the  two  bulbs,  so  that  what  is  con- 
tained in  the  cloth  cannot  be  seen.     We  have  now  a  structure 
like  the  heart,  but  we  know  its  structure.     We  know  that  it 
consists   of   two    pumps  wrapped    together  and  working  to- 
gether ;  that  is,  by  the  same  stroke,  but  with  two  wholly  inde- 
pendent currents. 

Reason  for  Injecting  the  Arteries.  —  The  arteries  and 
veins,  unless  distended  with  blood,  are  so  nearly  of  the  same 


66  INJECTING  MATERIALS. 

color  as  the  surrounding  tissues  that  it  is  difficult  to  distin- 
guish them.  Hence  it  is  very  desirable  to  rill  them  with  some 
colored  substance. 

The  following  starch  preparation,  recommended  by  Wilder 
and  Gage  in  their  admirable  work,  "  Anatomical  Technology," 
has  been  found  very  satisfactory  :  - 

STARCH  INJECTION  MASS. 

Dry  starch  ("Laundry"  is  good) .     .  100  c.  c. 

Water,  or  a  2$  percent  aqueous  solution  of  chloral  hydrate  100  c.  c. 

Alcohol  (95  per  cent) 25  c.  c. 

Color  mixture  (as  given  below) 25  c.  c. 

"After  thoroughly  mixing  the  mass,  it  should  be  filtered 
through  one  or  two  thicknesses  of  moistened  paper  cambric. 
To  prevent  the  starch  from  settling,  the  cloth  should  be  tilted 
from  side  to  side,  or  the  mass  may  be  stirred  during  the  filtra- 
tion. If  the  mass  is  not  freshly  prepared  for  every  injection, 
the  stock  mass  should  be  filtered  occasionally,  to  remove  hair 
or  any  other  object  that  might  clog  the  cannula. 

"  Since  almost  any  animal  injected  may  afford  some  organ 
worth  preserving,  it  seems  better  to  employ  permanent  colors 
in  tingeing  the  mass.  Among  these  wrhich  are  available,  the 
following,  probably,  are  preferable  :  vermilion,  red  lead  ultra- 
marine, Berlin  blue,  chrome  orange,  yellow,  or  green. 

PREPARATION  OF  THE   COLOR. 

Dry  color 100  c.  c. 

Glycerin 100  c.  c. 

Alcohol  (95  per  cent) 100  c.  c. 

"  To  avoid  lumps,  which  would  clog  the  cannula  or  small 
blood  tubes,  the  color  should  be  thoroughly  ground  in  a  mortar. 
It  should  be  stored  in  a  well-stoppered  bottle,  and  is  prepared 
for  use  by  simply  shaking.  If  permanent  preparations  are 


INJECTION   OF  THE  ARTERIES.  67 

not  to  be  made,  the  mass  may  be  stained  by  aniline  of  the 
desired  color." 

Excellent  results  have  been  obtained  by  the  use  of  carmine 
in  coloring  the  mass  for  injecting  the  arteries,  and  Berlin  blue 
or  Prussian  blue  for  the  veins. 

Kill  a  cat  or  rabbit  with  ether  or  chloroform,  by  putting 
the  animal  into  a  tight  box  or  jar  with  a  sponge  containing 
a  teaspoonful  of  the  anesthetic.  When  the  animal  is  dead, 
open  the  thorax  by  cutting  across  the  posterior  ends  of  the 
breast-bone,  and  through  the  costal  cartilages  on  each  side,  be- 
ing careful  not  to  cut  the  mammary  artery  which  runs  along 
the  inside  of  the  breast-bone  on  each  side.  The  mammary 
artery  should  be  ligated  just  under  the  anterior  end  of  the 
breast-bone.  Now  cut  away  the  breast-bone.  The  breast- 
bone may  be  simply  turned  forward,  and  in  this  case  it  will 
not  be  necessary  to  ligate  the  arteries. 

Find  the  aorta,  and  clear  away  any  tissues  that  may  obscure 
its  base.  Pass  a  ligature  under  the  aorta  here,  but  do  not  tie 
until  the  cannula  is  inserted.  Cut  a  small  slit  in  the  apex 
of  the  left  ventricle.  Have  in  readiness  several  cannulas  (or 
nozzles  of  a  brass  syringe)  of 
different  sizes,  made  by  draw- 
ing out  glass  tubing.  Each 
cannula  should  have  a  distinct 
neck,  so  that  it  may  be  tied  in 
firmly.  Insert  the  cannula 
through  the  ventricle  into  the  Fig.  20.  Surgeon's  Knot. 

base    of   the   aorta.      Now    tie 

the  cannula  firmly  by  the  surgeon's  knot,  made  by  crossing 
the  two  ends  of  the  thread  twice  instead  of  once,  as  in  the 
ordinary  knot ;  draw  firm  with  a  slight  sawing  motion,  but 
do  not  tie  again.  (See  Fig.  20.) 

For  injecting,  use  a  good  brass  syringe,  if  it  can  be  had;  a 


68 


INJECTING  APPARATUS. 


white  metal  syringe  does  fairly  well,  or  the  following  method 
may  be  employed  :  Place  a  good-sized  glass  funnel  in  a  large 
ring  of  a  retort  stand.  Slip  a  piece  of  black  rubber  tubing 
over  the  tube  of  the  funnel,  and  fasten  it  on  firmly  with 
cord  or  small  wire.  Put  a  pinchcock  on  the  lower  end  of 
the  tube.  Now  pour  the  starch  injection  mass  into  the  funnel. 


Glass  Funnel 


Glass  Cannula 


i ;.,:;.       :      [/ 


Fig.  21.     Injecting  Apparatus. 

Loosen  the  pinchcock,  and  let  a  little  of  the  mass  run  out,  to 
be  sure  that  the  tube  is  full.  Now  slip  the  end  of  the  tube 
on  the  cannula,  loosen  the  pinchcock,  and  inject  by  "  strip- 
ping "  the  rubber  tube  ;  or  the  process  might  well  be  described 
by  the  term  "  milking,"  as  it  is  like  that  process.  Hold  the 
upper  part  of  the  tube  with  one  hand,  and  with  the  other  the 
mass  may  be  driven  into  the  aorta.  One  great  advantage  of 
this  method  over  the  use  of  a  syringe,  is  that  the  operator 


ARTERIES  AND    VEINS.  69 

constantly  feels  the  degree  of  resistance ;  for  the  pressure  is 
given  directly  by  the  fingers,  instead  of  through  a  piston. 
Another  advantage  is  that  the  retort  stand  holds  itself;  and 
if  it  becomes  necessary  to  stop  the  pressure  at  any  time,  the 
pinchcock  may  be  applied  to  the  tube,  and  both  hands  are 
free  for  any  needed  adjustment,  while  everything  is  held  in 
readiness  to  go  011  with  the  work  after  simply  loosening  the 
pinchcock.  If  a  number  of  specimens  are  to  be  injected  at 
one  time,  a  separate  caimula  may  be  used  for  each  one,  and 
the  lower  end  of  the  tube  simply  transferred  from  one  to  the 
other.  If  desired,  the  mass  may  easily  be  stirred,  or  emptied 
from  the  funnel.  The  cannula  may  be  removed  after  ligatur- 
ing the  aorta,  or  a  piece  of  rubber  tubing  slipped  over  the 
cannula  and  tied.  In  any  case,  it  is  necessary  to  prevent  reflow 
of  the  mass  until  it  hardens. 

The  Distribution  of  the  Arteries  and  Veins  in  the  Cat 
or  Rabbit.  (Injected.)  —  1.  The  main  artery,  the  Aorta,  is 
a  thick-walled  tube,  springing  forward  from  the  center  of  .the 
base  of  the  heart.  It  soon  arches  over  to  the  left,  and  runs 
along  the  middle  .of  the  dorsal  wall  of  the  chest  cavity. 

2.  At  the  bend,  or  Arch,  the  aorta  gives  off  two  branches 
(three  in  man).     The  first  of  these  soon  subdivides,  giving  off 
a  branch  to  the  right  f orelimb,  the  Right  Subclavian  artery ;  two 
branches  running  along  the  side  of  the  windpipe  are  the  Right 
and  Left  Carotid  arteries.    The  second  branch  of  the  aorta  runs 
to  the  left  f  orelimb,  and  is  the  Left  Subclavian  artery. 

3.  During  its  course  through  the  thorax  the  aorta  is  called 
the  Thoracic  Aorta.     Trace  it  to  the  point  where  it  runs  through 
the  diaphragm.    It  then  becomes  the  Abdominal  Aorta.    Turn  the 
stomach  and  intestine  over  to  the  right,  and  observe  the  ab- 
dominal aorta  running  along  the  dorsal  wall  of  the  abdomen. 
Just  posterior  to  the  diaphragm,  a  branch  is  given  off  which 
subdivides,  and  gives  branches  to  the  stomach,  liver,  and  spleen. 


70  ARTERIES  AND    VEINS. 

Farther  back  a  large  branch  is  given  off  to  the  small  intes- 
tines. Follow  it  as  it  branches  through  the  Mesentery.  This 
is  the  Anterior  Mesenteric  Artery.  Find  the  branches  of  the 
aorta  that  lead  to  the  kidneys,  the  Renal  Arteries.  Some  other 
branches  may  be  seen  j  and  finally  the  aorta  divides  into  two 
large  branches,  the  Common  Iliacs  supplying  the  two  hind-limbs. 

4.  Turn  the  stomach  and  intestines  to  the  left,  and  observe 
the  two  veins  running  forward  from  the  two  hind-limbs.    These 
are  the  two  External  Iliac  Veins.     By  their  union  they  form  the 
Postcaval  Vein  (formerly  called  the  Vena  Cava  Inferior). 

5.  Observe  the  veins  from  the  kidneys,  the  Renal  Veins. 

6.  Trace  the  postcaval  vein  to  the  liver.     Observe  the  vein 
that  gathers  the  blood  from  the  intestine,  the  Mesenteric  Vein. 
This  vein  is  joined  by  a  vein  from  the  stomach,  the  Gastric 
Vein,  one  from  the  spleen,  the  Splenic,  and  one  from  the  pan- 
creas, the  Pancreatic;   together  these  form  the   Portal  Vein, 
which  empties  into  the  liver.     Unlike  other  veins,  the  portal 
vein  subdivides,  distributing  the  blood  through  the  liver.     The 
blood  thus  distributed  through  the  liver  is  recollected,  and  by 
the  Hepatic  Veins  joins  the  postcaval  vein,  close  to  the  dia- 
phragm, and  almost  wholly  concealed  by  the  liver. 

7.  The   postcaval   vein  passes  by  the  liver,  through  the 
diaphragm,  and  on  to  the  right  auricle. 

8.  On  removing  the   skin  of   the  neck,  there  should   be 
found  on  each  side  the  large  Jugular  Vein.     Each  of  these  is 
formed  by  the  union  of  the  Internal  and  External  Jugular 
veins. 

9.  Just  before  each  jugular  vein  enters  the  chest  cavity  it 
is  joined  by  a  vein  coming  from  the  corresponding  fore-limb, 
the  Right  and  Left  Subclavian  Veins.     The  union  on  each  side 
forms  the  Innominate  Vein.     The  two  innominate  veins  unit- 
ing make  the  Precaval  Vein,  which  enters  the  right  auricle. 
In  the  rabbit  there  are  two  precaval  veins. 


DISTRIBUTION   OF  ARTERIES  AND    VEINS. 


71 


External  Jugular  Vein 
C  Internal  Jugular  Vein 

2  Subclavian  Artery 

Subclavian  Vein 

Carotid  Artery 


Aorta 
III  Precaval  Vein 


IV   Postcaval  Vein 


Gastric  Artery 
Splenic  Artery 
Hepatic  Artery 
Pancreatic  Artery 


g  Renal  Veins 
5  Renal  Arteries 


7  Iliac  Arteries 
i  Uiac  Veins 


Fig,  22.    Distribution  of  Arteries  and  Veins, 


72  ACTION   OF  THE  HEART. 


HOW    THE    BLOOD    IS    PUMPED. 

The  Action  of  the  Prog's  Heart.  —  Before  reading  the 
description  of  the  action  of  the  heart,  it  will  pay  to  see  the 
action  of  the  frog's  heart. 

Kill  a  frog  as  directed  on  page  13,  and  destroy  its  brain  and 
spinal  cord.  Carefully  open  the  body  cavity,  and  lay  bare  the 
heart  without  injuring  it.  Its  beats  will  be  seen  to  be  com- 
posed of  three  parts  :  — 

1.  The  contraction  of  the  auricle. 

2.  The  contraction  of  the  ventricle. 

3.  These  actions  are  followed  by  a  pause,  after  which  No. 
1  and  No.  2  are  repeated. 

The  Rate  of  the  Heart-Beat.  —  The  heart  beats  about 
seventy-two  times  a  minute  in  men.  In  women,  about  eighty. 
At  birth  the  rate  is  from  one  hundred  and  thirty  to  one  hun- 
dred and  forty,  and  gradually  decreases  till  about  the  age  of 
twenty,  when  the  average  of  seventy-two  is  reached.  This 
rate  holds  till  old  age,  when  it  increases.  The  rate  is  in- 
creased by  muscular  activity,  food,  external  heat,  internal 
heat  (fever),  pain,  mental  excitement.  Music  accelerates  the 
pulse-rate.  The  pulse-rate  varies  during  the  twenty-four 
hours,  being  lowest  during  the  night,  and  highest  about 
eleven  A.M.  Certain  diseases  increase  the  frequency  of  the 
pulse.  Some  drugs  quicken  the  pulse-rate,  and  others  di- 
minish ^  it. 

The  Action  of  the  Heart.  —  The  heart  consists  of  muscle 
fibers  so  arranged  that  they  form  a  thick-walled  bag,  which 
stands  expanded  when  the  muscles  relax.  But  when  the 
fibers  shorten,  the  whole  heart  contracts,  and  the  cavity  is 
much  reduced  in  size,  if  not  entirely  obliterated,  and  the  blood 
is  forced  out. 

The  complete  action  of  the  heart  consists  of  three  parts, 


ACTION   OF  THE  HEART.  73 

the  contraction  of  the  auricle,  the  contraction  of  the  ventricle, 
and  the  pause. 

During  the  pause  the  blood  is  steadily  pouring  into  the 
auricles;  into  the  right  auricle  from  the  caval  veins,  into 
the  left  auricle  from  the  pulmonary  veins.  At  this  time  the 
curtain-like  valves  between  the  auricles  and  the  ventricles  are 
open,  and  their  flaps  hang  loosely  beside  the  walls  of  the  ven- 
tricles. The  blood,  therefore,  as  it  passes  into  the  auricles, 
passes  on  into  the  ventricles.  As  the  ventricle  fills,  the  valves 
float  up,  as  seen  in  the  experiment  of  pouring  water  into  the 
ventricle.  When  the  ventricle  is  full,  but  not  stretched,  and 
the  auricle  partly  full,  the  auricle  suddenly  contracts,  thus 
forcing  more  blood  into  the  ventricle,  and  distending  it.  At 
the  same  time  the  valves,  which  were  already  nearly  closed, 
are  tightly  closed  by  the  pressure  of  the  blood  which  is  forced 
up  behind  them.  The  flaps  of  the  valves  are  kept  from  going 
up  too  far  by  the  chordce  tendinece  and  by  the  papillary 
muscles. 

Next  comes  the  contraction  of  the  ventricle,  slower,  but 
more  powerful,  than  that  of  the  auricle.  As  the  walls  of  the 
ventricle  are  drawn  together,  the  blood  is  subjected  to  pres- 
sure. It  cannot  go  back  into  the  auricles,  for  the  more  it 
presses  against  the  valves,  the  more  tightly  they  are  closed. 
The  semilunar  valves  are  closed  by  back  pressure  in  the  aorta 
and  pulmonary  artery.  But  the  pressure  of  the  blood  in  the 
ventricles  is  so  much  greater  that  the  semilunar  valves  are 
forced  open,  and  nearly  all  the  blood  is  driven  out  of  the  ven- 
tricles ;  from  the  right  ventricle  into  the  pulmonary  artery, 
and  from  the  left  ventricle  into  the  aorta. 

While  the  ventricles  are  contracting  and  forcing  their  blood 
out,  the  auricles  are  slowly  filling  by  the  steady  inflow  through 
the  veins. 

As  soon  as  the  ventricle  has  completed  its  contraction,  it 


74 


ACTION   OF  THE  HEART. 


dilates,  and  most -of  the  blood  that  has  accumulated  in  the 
auricle  simply  falls  into  the  ventricle.  The  dilating  ventricle 
exerts  a  slight  suction,  so  the  blood  is  in  part  drawn  into  the 
ventricle.  During  the  remainder  of  the  pause  the  blood  accu- 
mulates in  the  auricle  and  ventricle  till  the  auricle  again  con- 
tracts, and  the  cycle  is  repeated. 


Auricle 


Fig.  23.     Diagram  of  the  Heart,  Showing  the  Action  of  the  Values. 

The  time  taken  by  the  different  parts  of  the  heart-beat,  as 
near  as  can  be  measured,  are  about  as  follows  :  — 

Since  the  heart  beats  seventy-one  or  seventy-two  times  each 
minute,  each  beat  takes  about  eight-tenths  of  a  second  (.8) ;  of 
these  eight-tenths  the  auricle  takes  for  its  contraction  one- 
eighth  of  the  time  ;  that  is,  one-tenth  of  a  second  (.1)  ;  the  con- 
traction of  the  ventricle  occupies  three-eighths  of  the  time,  or 
three-tenths  of  a  second  (.3),  while  the  pause  fills  the  rest  of 
the  time ;  that  is,  four-eighths,  or  one-half,  of  the  whole  time 
of  the  entire  heart-beat,  or  four-tenths  of  a  second  (.4).  Let 
us  call  the  time  required  for  the  complete  heart-beat  the 
heart's  day.  Of  course  this  day  is  very  short,  less  than  a 
second.  If  we  suppose  it  to  be  twenty-four  hours,  we  can 


THE  HEART-BEAT.  75 

more  easily  see  how  much  of  the  time  the  heart  is  actually  at 
work,  and  how  much  of  the  time  the  heart  is  resting :  — 

Auricle     contracting  (working)  |  of  the  time  — 3  h.,  resting  21  h. 
Ventricle  contracting  (working)  §  of  the  time  —  9  h.,  resting  15  h. 

No  part  of  the  heart,  therefore,  is  working  longer  than  a 
man  would  who  only  works  nine  hours  a  day.  Some  observers 
state  that  the  resting  period  is  even  greater  than  these  figures 
would  show. 

Since  the  contraction  of  the  ventricles  immediately  follows 
that  of  the  auricles,  one-half  of  the  time  is  occupied  by  the 
whole  beat  of  the  hsart,  and  during  half  the  time  the  whole 
heart  is  resting.  This  is  different  from  our  usual  statements 
regarding  the  work  of  the  heart.  We  hear  it  said  that  the 
heart  never  rests.  Its  work  and  rest  follow  each  other  at  such 
short  intervals  that  we  do  not  appreciate  the  interval  of  rest 
that  comes  between  the  successive  impulses  that  we  feel. 
Suppose  a  policeman  had  the  power  of  sleeping  at  will,  and 
that  he  slept  thirty  minutes  of  each  hour,  and  that  in  the  re- 
maining thirty  minutes  he  made  the  rounds  of  a  block.  If 
we  saw  him  passing  regularly  once  an  hour,  every  hour  of  the 
twenty-four,  we  might  suppose  that  he  did  not  sleep  at  all 
during  the  entire  time. 

The  Beat  of  the  Heart.  —  The  apex  of  the  heart  is  al- 
ways in  contact  with  the  chest  wall.  Consequently,  it  never 
strikes  it.  At  each  beat  it  pushes  hard  against  the  chest 
wall.  This  push  may  be  felt  and  seen,  and  is  called  the 
heart-beat. 

The  Sounds  of  the  Heart.  —  There  are  two  sounds  of 
the  heart :  — 

1.  A  short,  sharp  sound  made  by  the  closing  of  the  semi- 
lunar  valves. 

2.  Just  preceding  this  sound  a  longer,  duller  sound  may 


76 


ACTION   OF  LARGE  ARTERIES. 


be  heard,  during  the  contraction  of  the  ventricles.  This  is 
supposed  to  be  due  to  the  vibrations  of  the  walls  of  the  ven- 
tricles, and  of  the  large  valves. 

Action  of  the  Large  Arteries.  —  The  large  arteries  have 
in  their  walls  a  yellow  elastic  tissue.  When  the  blood  is 
forced  into  them  they  are  stretched.  As  soon  as  the  ventricle 
ceases  to  contract,  and  sends  no  more  blood  into  the  arteries, 
they  "  stretch  back."  We  should  not  say  contract,  for  it  is 
simply  an  elastic  reaction.  As  the  artery  reacts  it  presses  on 
the  blood,  and  hence  the  blood  tries  to  escape  in  every  possi- 
ble way.  It  cannot  go  back,  for  it  fills  the  pockets  of  the 
semilunar  valves,  and  closes  them  with  a  click.  A  rapid 
wave  is  sent  forward  that  gives  the  pulse,  and  a  slower  but 
still  rapid  stream  flows  along  the 
arteries,  through  the  pulmonary 
artery  to  the  lungs,  and  through 
the  aorta  and  its  branches  to  all 
the  other  parts  of  the  body. 

The  elastic  reaction  of  the  ar- 
teries thus  makes  steady  the  flow 
of  blood  which  is  intermittent  as  it 
leaves  the  heart. 

Action  of  the  Medium-Sized 
Arteries.  —  Each  organ  requires 
a  supply  of  blood  in  proportion  to 
its  activity.  An  actively  working 

organ,  like  the  brain,  demands  much  more  blood  than  bone 
practically  inactive.  Further,  working  tissues,  such  as  the 
brain  and  muscles,  need  a  great  deal  more  blood  while  they 
are  at  work  than  when  they  are  resting.  An  organ  needing 
a  constant  large  supply  of  blood  might  secure  this  by  having  a 
large  artery.  But  how  can  the  supply  be  regulated  so  that  an 
organ  may  receive,  now  more,  now  less,  according  to  its  needs? 


Nucleus 


•'•'•'••'•""••    Isolated   Fibers 


Fibers  Joined 


Fig.  24.     Plain  (Unstriated)  Mus- 
cular Fibers  from  the  Bladder. 


ACTION   OF  SMALL  ARTERIES. 


77 


This  is  regulated  by  the  medium-sized  arteries  leading  to 
the  parts.  In  the  walls  of  the  small  and  medium-sized  arte- 
ries are  muscle  fibers  of  a  different  kind  from  those  of  the 
skeleton.  These  fibers  are  spindle-shaped,  as  shown  in  Fig.  24, 
and  do  not  have  the  cross-markings  of  the  fibers  of  the  skele- 
tal muscles ;  they  are  in  consequence  called  Non-striated,  Smooth 

Connective  Tissue 


Endothelium 


uclei 


Muscle  Fiber 


Fig.  25.    Plain  Muscle  Fiber.    Isolated  and  in  wall  of  Artery. 

or  Plain  Muscle  Fibers.  They  are  arranged  circularly  in  the 
walls  of  the  arteries.  These  fibers  have,  in  common  with  all 
muscle  fibers,  the  power  of  shortening,  but  at  a  much  slower 
rate  than  the  striated  fibers.  When  they  shorten  they  reduce 
the  size  of  the  artery,  and,  therefore,  for  the  time,  less  blood 
can  flow  through  the  artery.  When  the  muscle  fibers  cease  to 
shorten,  the  artery  widens,  and  allows  more  blood  to  pass 
through  it. 

To  illustrate  the  action  of  the  muscles  in  the  walls  of  an 
artery,  let  the  water  run  through  a  hose  or  large  rubber  tube. 
Now,  if  a  row  of  persons  take  hold  of  this  tube,  the  grip  of 
their  hands  is  like  that  of  the  muscles.  When  the  hands 


78 


STRUCTURE  OF  ARTERIES. 


Endothelium 


tighten  their  grip,  the  caliber  of  the  hose  or  tube  is  dimin- 
ished, and  less  water  is  allowed  to  flow  through  it.  When  the 
hands  relax,  the  tube,  being  elastic,  allows  more  liquid  to  flow 
through  it. 

To  represent  a  small  artery,  take  a  small  thin-walled  rub- 
ber tube,  and  wind  a  red  thread  around  it.  Now,  if  the  thread 
could  be  made  to  shorten,  it 
would  diminish  the  caliber  of 
the  tube.  The  representation 
wouldt  be  more  exact  if  the 
thread  were  cut  into  many 
short  pieces,  and  if  each  piece 
were  thicker  in  the  middle,  and 
were  then  glued  to  the  tube. 
If  the  whole  were  covered  by 
a  layer  of  tissue  paper  the 
structure  of  the  artery  would 
be  roughly  represented.  Each 
of  the  plain  muscle  fibers  has 
a  Nucleus  near  its  center. 

These  plain  muscle  fibers  are 
further  like  the  skeletal  mus- 
cles in  that  they  are  under  the  control  of  the  nerves,  but 
they  are  involuntary  in  their  action.  We  cannot  interfere 
with  the  action  of  these  muscles,  no  matter  how  strongly  we 
may  will  to  do  so.  Without  our  thinking  about  it,  more  blood 
goes  to  the  muscles  of  the  legs  when  we  walk,  more  to  the 
brain  when  we  are  studying,  to  the  digestive  organs  after 
eating,  etc. 

The  Blood-Flow  in  the  Capillaries.  —  The  arteries  divide 
and  subdivide,  and  become  capillaries,  which  have  connecting 
branches,  forming  a  close  network  of  tiny  thin-walled  tubes. 
These  penetrate  and  pervade  nearly  every  tissue  of  the  body. 


The  Oute 
Coat 


Fig.  26.     Coats  of  a  Small  Artery. 
(After  Landois  &  Stirling.) 


BLOOD-FLOW  IN   CAPILLARIES. 


79 


Vein 


Artery 


Fig.  27.     Cross  Section  of  Small  Artery 
and  Vein. 


The  blood  cannot  do  its  work  till  it  gets  into  the  tissues,  and 
to  reach  the  tissues  it  must  soak  through  the  walls  of  the 
capillaries.  The  work  of  the  heart  and  arteries  is  to  keep  a 

steady  flow  of  blood  through 
the  capillaries,  that  the  tis- 
sues may  be  constantly  sup- 
plied. 

How  is  it  that  the  jerky 
action  of  the  heart,  at  each 
contraction  sending  a  jet  of 
blood  into  the  arteries,  — 
shown  by  a  spurt  when  an 
artery  is  severed,  and  also 
indicated  by  the  intermittent 
pulse,  —  how  is  this  inter- 
mittent flow  converted  into  the  steady,  uniform  current  that 
we  have  seen  in  the  capil- 
laries ? 

A  few  experiments   may 
make  this  matter  more  clear. 
Material :  — 

1.  A  common  rubber  syr- 
inge. 

2.  A    glass    tube    three 
feet    long    and    seven-six- 
teenths of    an  inch    outside 
diameter. 

3.  Four    inches    of    the 
same    size  glass  tubing,  for 
making  connections. 

4.  Several  nozzles,  made 

of  the  same  size  glass  tubing,  all  fine,  but  of  varying  degrees 
of  fineness. 


Surface  View 


Nuclei 


Cross  Sections 


Longitudinal  Section 

Fig.  28.    Capillaries,  composed  of  a  single 
layer  of  cells. 


80  EXPERIMENTS    WITH  BLOOD-FLOW. 

5.  India-rubber  tubing,  twelve  feet,  three-eighths  of  an 
inch  inside  diameter.  This  should  be  black,  pure  gum,  rubber 
AY  Inch  is  more  highly  elastic  than  the  other  kinds. 

G.    Three  feet  of  rubber  tubing,  same  size  as  above. 

7.  Four  inches  of  white  rubber  tubing,  same  size  as  above, 
for  making  connections. 

In  all  the  experiments,  have  one  of  the  students  assist  by 
holding  the  outlet  tube,  so  that  (1)  all  the  members  of  the 
class  may  see  the  stream,  and  (2)  that  the  stream  may  be 
suitably  directed,  as  into  a  pail  or  sink. 

Count  aloud,  to  mark  the  exact  time  of  each  compression 
of  the  bulb,  so  the  students  can  compare  this  with  the  time 
and  duration  of  the  jets  of  water. 

Be  very  careful  to  use  perfectly  clean  water,  as  any  fine 
particles  of  sediment  drawn  into  the  tube  are  likely  to  clog 
the  fine  outlet  of  the  nozzle.  And  it  is  well  to  take  the 
further  precaution  not  to  let  the  supply  tube  touch  the  bottom 
of  the  water-supply  dish,  as  some  fine  sediment  may  get  in 
in  spite  of  previous  care. 

EXPERIMENT  1. — Remove  the  nozzle  of  the  syringe,  and  put 
in  its  place  the  long  glass  tube.  Work  the  syringe,  and  note 
that  the  jet  is  jerky,  following  each  contraction  of  the  bulb. 

EXPERIMENT  2.  —  Substitute  the  rubber  tube,  three  feet 
long,  for  the  glass  tube.  On  working  the  bulb  the  stream 
will  be  found  intermittent. 

EXPERIMENT  3.  —  Take  off  the  rubber  tube  and  replace  the 
glass  tube,  adding  the  nozzle.  Here  the  pressure  will  be  so 
great  that  it  is  likely  to  push  off  the  nozzle  unless  the  assis- 
tant holds  it  firmly.  It  could  be  tied  on,  but  this  takes  more 
time.  On  working  the  bulb,  greater  effort  must  be  made  on 
account  of  the  resistance  caused  by  the  narrower  outlet. 

EXPERIMENT  4.  —  Once  more  substitute  the  rubber  tube, 
this  time  with  a  glass  nozzle  in  its  end.  Now,  on  working 


EXPERIMENTS    WITH  BLOOD-FLOW.  81 

the  bulb,  resistance  will  be  felt,  and  the  stream  will  be  con- 
stant, or  nearly  so,  and  will  continue  for  some  time  when  the 
bulb  is  no  longer  worked.  This  is,  clearly,  because  the  rub- 
ber has  been  stretched,  chiefly  laterally,  and  is  now  "  stretching 
back."  That  is,  by  the  elastic  reaction  of  the  rubber  tube  the 
jerky  action  of  the  bulb  is  converted  into  the  steady  flow  that 
we  see.  In  the  first  experiment  we  had  a  rigid  tube  and  prac- 
tically no  resistance.  In  the  second,  although  the  tube  was 
elastic,  there  was  no  resistance,  so  the  elasticity  was  not 
brought  into  play.  In  the  third,  there  was  resistance,  but  the 
tube  was  inelastic.  In  the  fourth,  the  resistance  brought  into 
play  the  elasticity  of  the  rubber  tube,  and  the  elastic  reaction 
of  the  tube  continues  (so  to  speak)  the  action  of  the  bulb  be- 
tween two  successive  strokes.  In  this  experiment  the  pulse 
can  be  felt  in  the  tube. 

EXPERIMENT  5.  —  Repeat  the  last  experiment,  except  with 
the  change  of  taking  the  rubber  tube  ten  or  twelve  feet  long. 
Double  this  along  a  table  so  that  the  nozzle  lies  close  to  the 
bulb.  Let  each  pupil  take  hold  of  the  tube  near  the  bend,  and 
then  advance  toward  the  bulb,  holding  one  part  of  the  loop 
in  each  hand,  noting  the  time  at  which  the  pulsation  is  felt  in 
the  two  parts  of  the  loop.  Let  the  teacher  or  the  person  who 
works  the  bulb  count  aloud  to  give  the  time  of  each  compres- 
sion of  the  bulb,  so  that  it  can  be  compared  with  the  time  of 
the  pulsations.  Observe  (1)  whether  the  pulse  occurs  at  the 
instant  of  the  compression  of  the  bulb;  (2)  whether  the  pulse 
is  felt  at  the  same  instant  by  the  two  hands  when  one  hand 
holds  the  tube  near  the  bulb  and  the  other  hand  near  the 
nozzle.  Compare  with  this  the  intervals  between  the  heart- 
beats and  the  pulse  as  felt  at  (1)  the  temple,  (2)  the  wrist, 
(3)  the  ankle. 

The  pulse  in  the  artery  and  in  the  rubber  tube  must  not  be 
confounded  with  the  blood-flow  itself.  The  pulse  is  a  wave 


82  VALVES  IN  THE   VEINS. 

running  much  faster  than  the  blood  current.  To  prove  this 
point,  make  the  following  experiment :  Pour  a  little  red  ink 
into  a  dish  of  water,  and  while  working  the  bulb  of  the  syr- 
inge as  in  Experiment  4,  quickly  transfer  the  supply  tube 
to  the  colored  liquid.  The  pulse  will  continue  unchanged,  but 
it  may  take  several  strokes  before  the  colored  liquid  issues 
from  the  nozzle. 

The  pulse  may  be  compared  to  the  shock  that  runs  through 
a  freight  train.  When  the  engine  bumps  against  the  first  car, 
this  car  strikes  the  next,  and  so  on  through  the  whole  length 
of  the  train.  The  shock  has  gone  the  length  of  the  train,  but 
no  car  has  moved  more  than  a  few  feet. 

The  Veins.  —  The  capillaries,  after  penetrating  the  tissues, 
reunite  to  form  small  veins,  till  finally  two  great  veins,  the 
Caval  Veins,  Precaval  and  Postcaval,  return  the  blood  to  the 
heart.  The  veins,  like  the  arteries,  are  smooth  inside  and 
elastic  (though  less  elastic  than  the  arteries).  They  are 
thinner  than  the  arteries,  and,  in  consequence,  collapse  when 
the  blood  flows  out  of  them,  whereas  the  larger  arteries  stand 
open,  after  they  are  emptied  of  blood. 

The  Valves  in  the  Veins.  —  The  only  valves  in  the  ar- 
teries are  those  which  we  have  seen  at  the  beginning  of  the 
aorta  and  pulmonary  artery.  Many  of  the  veins  have  similar 
pocket-like  valves,  though  lose  strong  than  those  of  the  ar- 
teries. Dissect  back  the  skin  from  the  throat  of  the  cat  or 
the  rabbit,  till  the  Jugular  veins  are  well  exposed.  Let  the 
head  of  the  animal  hang  over  the  edge  of  the  table,  and  ob- 
serve that  as  the  blood  passes  toward  the  head  it  causes  a 
marked  bulging  at  certain  points.  With  the  handle  of  the 
scalpel  gently  stroke  the  vein  toward  the  head,  watching 
these  swellings.  Dissect  out  the  vein  from  the  head  to  the 
shoulder.  Insert  the  nozzle  of  a  syringe,  first  into  one  end, 
then  into  the  other,  and  note  the  effect  of  sending  a  stream 


EFFECT  OF   VENOUS    VALVES. 


83 


of  water  in  the  two  directions.  Cut  the  vein  open  along  one 
side,  and  pin  it  to  a  piece  of  shingle,  with  the  inner  side  out. 
The  thin,  pocket-like  valves  ought  now  to  be  seen.  They  are 
usually  in  pairs,  but  sometimes  single  or  in  threes.  It  is  im- 
portant to  note  that  they  all  have  the  mouths  of  the  pockets 
toward  the  heart,  so  that  the  blood  flows  freely  toward  the 
heart,  but  is  prevented  from  flowing  the  other  way  on  account 
of  the  filling  of  the  valves  by  the  reflow  of  the  blood  stream. 
When  the  blood  is  flowing  through  the  veins  toward  the 

heart   the  valves   lie    against 
the  walls  of  the  veins. 

The  valves  are  most  nu- 
merous in  the  medium-sized 
veins,  and  especially  in  the 
veins  of  the  extremities  ; 
more  abundant  in  the  leg  than 
in  the  arm.  Valves  are  absent 
from  the  Caval  and  some 
other  veins,  and  from  the  very 
small  veins.  While  experi- 
menting with  the  vein,  to  see 
the  valves  and  their  actions,  note  also  the  smoothness  of  the 
lining.  Test  also  the  elasticity  of  the  veins. 

Effect  of  Pressure  on  the  Veins.  —  Since  the  valves  in 
the  veins  open  toward  the  heart,  any  intermittent  pressure  on 
the  veins  helps  to  push  the  blood  on  toward  the  heart.  The 
valves  are  most  numerous  in  the  superficial  veins  and  those  of 
the  muscles.  The  pressure  of  the  muscles  during  their  action 
(thickening  while  shortening)  produces  pressure  on  the  veins ; 
and  as  the  muscles  act  for  a  short  time  only,  and  then  relax, 
this  alternate  compression  and  release  aids  very  considerably 
in  moving  the  blood  on  toward  the  heart.  It  is  worthy  of 
remark  that  this  effect  is  more  pronounced  at  the  time  the 


Open  Shut 

Fig.  29.     Venous  Values. 


84  EATE   OF  BLOOD-FLOW. 

muscles  need  the  most  active  circulation ;  namely,  when  they 
are  in  action,  and  are  using  the  most  blood.  The  heart  has 
power  enough  to  pump  the  blood  clear  around  from  each  ven- 
tricle to  the  auricle  of  the  other  side  of  the  heart;  but  this 
outside  aid  comes  in  good  play  to  relieve  the  heart  at  a  time 
when  it  has  an  unusual  amount  of  work  to  do,  as  when  one  is 
using  a  large  number  of  muscles  vigorously. 

"  Every  active  muscle  is  a  throbbing  heart,  squeezing  its 
blood  tubes  empty  while  in  motion,  and  relaxing  so  as  to  allow 
them  to  fill  up  anew." 

Rate  of  Blood-Flow  in  the  Arteries,  Capillaries,  and 
Veins.  —  The  blood  flows  most  rapidly  in  the  arteries,  slowest 
in  the  capillaries.  Why  is  this  ? 

When  an  artery  divides,  the  two  branches  taken  together 
are  larger  than  the  one  artery  that  divided  to  form  them. 
Stated  more  exactly,  we  would  say  that  the  sum  of  the  area 
of  the  cross-sections  of  the  branches  is  greater  than  the  area 
of  the  cross-section  before  branching.  Hence,  as  the  blood 
flows  on,  it  is  continually  entering  wider  and  wider  channels ; 
and  we  are  told  that  the  united  cross-section  of  all  the  capil- 
laries fed  by  the  aorta  is  several  hundred  times  that  of  the 
aorta  itself. 

If  we  walk  along  a  stream  we  see  that  the  channel  varies 
considerably  in  width  and  depth.  Where  the  channel  is  large, 
whether  from  increased  width  or  depth,  there  the  current  is 
slower;  but  wherever  the  channel  is  reduced,  the  current  is- 
more  rapid.  So  the  stream  in  the  relatively  narrow  artery 
is  swift.  In  the  capillaries,  although  any  individual  chan- 
nel is  small,  these  channels  all  together  are  wide;  the  result 
is  the  same  whether  a  river  widens  out  into  a  single  lake,  or 
divides  into  a  great  number  of  channels  running  past  innu- 
merable islands.  All  the  tissues  of  the  body  may  be  regarded 
as  so  many  islands  lying  between  the  capillary  streams. 


PLAN   OF  CIRCULATION. 


85 


When  the  blood  re-collects  in  the  veins  it  is  entering  nar- 
rower channels,  and  its  rate  is  quickened ;  but  as  the  veins  are 
wider  than  the  arteries,  the  stream  does  not  enter  the  heart 
with  the  velocity  with  which  it  left  that  organ.  The  veins 
hold  more  blood  than  the  arteries,  and  in  dissecting  the  cat 


Pulmonary  Vein     — 


Left  Auricle    


Left  Ventricle 


Aorta  - 


Digestive  Tube 


Pulmonary  Artery 
Lymph  Vein 

Right  Auricle 


•   Right  Ventricle 
..  Caval  Vein 

•••  Liver 


Fig.  30.     Plan  of  Circulation.     (Dorsal  View?) 

or  rabbit  it  will  be  noticed  that  the  arteries  are  emptied  of 
blood ;  that  the  tissues  of  most  of  the  organs  are  fairly  free 
from  blood ;  but  that  the  great  veins,  such  as  the  caval  veins, 
are  full. 


86  BLUSHING. 

If  the  blood  tubes  leaving  the  heart  could  all  be  united, 
they  would  be  best  represented  by  a  funnel  with  its  tube  con- 
nected with  the  heart.  If  another  funnel  were  placed  with 
its  mouth  to  the  mouth  of  the  first,  their  point  of  union,  the 
widest  point,  would  represent  the  capillaries;  and  if  the 
second  funnel  had  a  wider  tube  than  the  first,  it  would  fairly 
represent  the  veins  which  return  the  blood  to  the  heart. 

Nourishment  of  the  Walls  of  the  Heart  and  Blood 
Tubes.  —  The  Cardiac  (Coronary)  arteries  send  blood  into  the 
muscular  walls  of  the  heart,  and  these  arteries,  like  others, 
divide,  forming  capillaries,  through  which  the  heart  muscle  is 
nourished.  The  Cardiac  veins  return  the  blood  to  the  right 
auricle. 

The  larger  arteries  and  veins  also  have  small  blood  tubes 
in  their  walls  which  supply  them  with  blood. 

The  statements  which  have  been  made  concerning  the 
action  of  the  heart,  and  the  blood  tubes  connected  with  it, 
apply  equally  to  both  halves  of  the  heart,  which  work  simul- 
taneously ;  the  chief  difference  in  the  two  sides  of  the  heart 
is  that  the  right  side  pumps  dark  blood,  while  the  left  pumps 
bright  blood. 

The  left  ventricle  is  much  stronger,  as  it  has  to  pump  the 
blood  against  so  much  greater  resistance. 

Blushing.  —  How  is  it  that  the  face  sometimes  flushes  so 
suddenly  ?  Because  of  some  emotion,  you  say.  But  how 
does  the  emotion  bring  this  about  ? 

The  following  experiment,  that  has  been  repeatedly  made 
on  the  rabbit,  may  help  us  to  answer  the  question.  If  the 
sympathetic  nerve,  in  the  neck,  which  sends  branches  to  the 
head,  be  cut,  the  ear  of  that  side  at  once  grows  red;  i.e.,  it 
blushes.  But  if  the  end  of  the  nerve  connected  with  the  ear 
be  stimulated,  the  ear  becomes  pale.  We  have  already  learned 
about  the  muscles  in  the  wall  of  the  arteries,  and  their  action. 


BL  U  SUING.  87 

We  are  now  prepared  to  understand  that  in  the  normal  condi- 
tion nervous  impulses  are  acting  on  these  muscles,  keeping 
them  partly  shortened,  and  so  keeping  the  arteries  of  a  mod- 
erate size.  When  the  nerve  is  cut,  these  nervous  impulses 
are  interrupted,  and  the  muscle  fibers,  being  no  longer  stimu- 
lated, relax,  and  allow  the  artery  to  widen,  and  so  permit 
more  blood  to  flow  through  it.  Thus  more  blood  goes  to  the 
parts  supplied,  and  they  become  redder,  and,  for  the  time  at 
least,  warmer. 

When  the  end  of  the  nerve  is  stimulated,  the  muscle  fibers 
are  made  to  shorten  and  diminish  the  caliber  of  the  artery, 
and  to  reduce  the  blood  supply ;  and  this  lessened  blood  sup- 
ply is  shown  by  the  pallor  and  coldness  of  the  part. 

Under  the  influence  of  varying  emotions,  the  caliber  of  the 
arteries  is  changed,  largely  through  the  nerves  of  the  sympa- 
thetic system. 

In  the  same  way,  through  the  sympathetic  system,  the 
blood  supply  of  all  the  organs  of  the  body  is  regulated.  Any 
organ  needing  more  blood  sends  a  message  (nerve  impulse)  to 
some  nerve  center ;  and  in  response  nerve  impulses  are  sent  to 
the  muscle  fibers  of  the  supplying  artery,  and  the  amount  of 
blood  sent  to  that  organ  is  regulated.  For  instance,  a  piece 
of  ice  is  laid  upon  the  skin  of  the  hand.  The  part  becomes 
pale,  as  the  arteries  have  become  narrowed.  If  this  action 
be  continued,  there  may  set  in  a  decided  reaction,  and  the 
part  become  more  red  than  usual  when  the  reaction  has  made 
the  artery  wider  than  it  was  before  the  constriction. 

As  there  is  only  a  certain  amount  of  blood  in  the  body,  it 
is  evident  that  if  one  organ  receives  an  extra  supply,  some 
other  organ  or  organs  must,  for  the  time,  receive  less.  For 
instance,  one  begins  to  walk  vigorously.  The  large  muscles 
of  the  lower  limbs  and  trunk  become  active,  and  they  need 
more  blood.  They  therefore  send  messages  to  some  nerve 


88  SYMPATHETIC  NERVES. 

center  (probably  in  the  spinal  cord)  ;  and  by  reflex  action  the 
arteries  supplying  the  lower  limbs  are  widened,  and  these 
muscles  receive  more  blood.  But  these  muscles  make  up  a 
very  considerable  part  of  the  weight  and  bulk  of  the  body. 
While  in  action  they  take  the  lion's  share  of  the  blood.  The 
brain,  at  such  a  time,  would  receive  less ;  and 
it  would  be  folly  to  expect  the  brain  to  work 
at  its  full  capacity  while  the  blood  was  called 
away  to  other  organs. 

When  we   exercise   vigorously  the  heart 
beats  faster,  and  this  of  itself 
would    tend    to    increase     the 

Sympathetic, 

blood  supply  to  all  organs.    But          Ganglia 
this  mechanism  of  widening  the 
channel  leading  to  the  working  organs,  while 
the  arteries  to  the  other  organs  are  made 
smaller,  or  at  least  are  not  enlarged,  solves 
the  problem  of  supplying  each  part  accord- 
ing  to  a   greatly  varying   need,  while   not 
sending  too  much  to  a  part  not  needing  it. 

When  we  sit  quietly  intent  upon  study, 
the  brain  has  a  larger  supply  of  blood,  and 
other  parts  now  have  less  ;  in  such  condition 
the  feet  may  easily  grow  cold. 

If  we  wish  to  draw  away  some  of  the 
blood  from  the  brain  after  prolonged  study, 
we  take  a  little  gentle  exercise  to  better  pre- 
pare for  Sleep.  Fig.  31.  Ventral  View 

Dissection  of  the  Sympathetic  Ner-       °f  sPinal  Cord  wiih 

Sympathetic  Ganglia 

vous  System.  —  In  a  cat  or  a  rabbit  open       of  one  side. 
the  chest  cavity,  and    pull   the   heart   and 
lungs  to  one  side.     Close  to  the  spinal  column  there  maj7  be 
seen  a  white  nerve  with  a  ganglion  for  every  rib.     This  is  the 


Carotid  Plexus 


Superior  Cervical  Ganglion  - 


Middle  Cervical   Ganglion 


Pharyngeal  Branches 
Cardiac  Branches 

Deep  Cardiac  Plexus 

Superficial  Cardiac   Plexus 


Solar  Plexus 


Aortic  Plexus 


_umbar  Ganglia 


Fig.  32.     Vertical  Section  of  Body,  showing  Sympathetic  Nerues  and  Ganglia  of  Right  Side  and 
their  Connection  with  the  Cerebro-Spinal  Nerues. 


90  CONTROL    OF  CIRCULATION. 

Gangliated  Nerve  Chain.  By  picking  away  a  little  tissue  it 
may  readily  be  seen  that  each  spinal  nerve  gives  a  branch  to 
this  system.  Find  the  sympathetic  chain  of  the  other  side. 
Trace  the  sympathetic  system  through  the  diaphragm  to  the 
Solar  Plexus  back  of  the  stomach.  Some  of  the  other  ganglia 
and  plexuses  may  be  discovered.  Turn  back  to  the  thorax, 
and  trace  the  chain  on  one  side  up  into  the  neck.  Some  large 
ganglia  will  be  found  by  following  in  this  direction, 

Control  of  the  Heart  and  Blood  Tubes  by  the  Ner- 
vous System.  —  We  know  that  certain  emotions  affect  the 
circulation  of  the  blood ;  for  instance,  blushing  and  pallor,  to 
which  reference  has  been  made.  Certain  emotions  may  also 
quicken  or  retard  the  action  of  the  heart.  Excessive  grief  or 
joy  has  produced  sudden  death  by  stopping  the  beat  of  the 
heart. 

Let  us  look  a  little  more  closely  at  that  part  of  the  nervous 
system  that  has  such  intimate  relation  to  the  blood  system. 

In  the  first  place,  the  action  of  the  heart  is  automatic. 
The  heart  of  the  frog  continues  to  beat  a  long  time  after  it  is 
removed  from  the  body.  This  is  regarded  by  many  as  due  to 
the  action  of  certain  ganglia  imbedded  in  the  walls  of  the 
heart,  especially  in  the  auricles ;  while  others  say  that  since 
the  ventricle,  in  which  no  ganglia  have  been  found,  may  beat 
independently  of  the  auricles,  rhythmic  contraction  is  charac- 
teristic of  heart  muscle,  and  that  we  are  at  present  unable  to 
explain  it. 

But  while  the  impulses  that  originate  the  action  of  the 
heart  arise  within  the  heart  itself,  still  the  beat  of  the  heart 
is  constantly  modified  by  nerve  impulses  reaching  it  from 
without. 

The  heart  receives  its  nerves  from  two  sources,  the  Sym- 
pathetic System  and  the  Pneumogastric  Nerves. 

The  Sympathetic  Nervous  System  consists  of  two  rows  of 


PNEUMOGASTRIC  NERVES. 


91 


Fig.  33.    Relation  of  Spinal  Cord  and 
Sympathetic  Nervous  System  (Diagram). 


ganglia  in  the  body  cavity,  one  along  each  side  of  the  spinal 
column,  receiving  branches  from  the  spinal  nerves,  and  sending 
branches  to  all  the  internal  organs  of  the  body,  —  the  heart  and 
lungs  in  the  thorax,  and  the 

Stomach,     intestines,     and     the  Sympathetic  Nerve  Chains 

other  organs  of  the  abdominal 
cavity.     In  many  places  these 
nerves  form  a  thick 
network    called    a 
plexus.      One    very 
large   plexus   is   on 
the    posterior    sur- 
face of   the    stomach,  and  is 
called  the  Solar  Plexus. 

The  Pneumogastric  Nerves 
are  a  pair  of  the  cranial  nerves 
arising  from  the  sides  of  the 
spinal  bulb ;  and,  passing  downward,  they  give  branches  to  the 

pharynx,  gullet,  and  stom- 
ach, the  larynx,  windpipe, 
and  lungs,  and  the 
heart.  Now,  what- 
ever  Other  function 
the  pneumogastric 
nerves  may  have,  they 
seem  to  have  the  power  of 
retarding,  or  stopping  al- 
together, the  beat  of  the 
heart ;  and  stimulation  of 
the  pneumogastric  nerves  may  make  the  heart  pause  in  a  re- 
laxed condition.  Other  nerves  may  quicken  the  heart-beat, 
but  the  pneumogastrics  are  regarded  as  a  brake  on  the  heart's 
action. 


Spinal  Cord 


Sympathetic 
Ganglion 


Fig.  34.     Ideal  Cross  Section  of  the 

Nervous  System.     (After  Lan- 

dois  &  Stirling.) 


INHIBITION  OF  THE  HE  AST. 


This  is  a  case   of    Inhibition.     It  is  well    known   that  a 
severe  blow  over  the  stomach  may  cause  one  to  faint  by  stop- 
ping the  heart.     This  is  due  to  Reflex  Inhibition  of  the  heart. 
The    blow   sends  a   nerve   impulse    by 
fibers  of  the  sympathetic  system  to  the 
center  in  the  spinal  bulb,  and  thence  an 
impulse  is  taken  by  the  pneumogastric 
nerves  to  stop  the  heart. 

In  the  experiment  with  the  rabbit's 
ear  we  saw  that  stimulating  the  sympa- 
thetic nerve  caused  the  ear  to  become 
pale.      This,  we  understand,  is  due  to 
the  constriction  of  the  arte- 
ries of  the  ear,  because  the 
nerves  have  made  the  muscle 
fibers  of  these  arteries  short- 
en.     Such   nerve   fibers   are 
called   Constrictors,   or  Vaso- 
constrictors.     They    run    in 
the    sympathetic   nerve,  but 
have  their  origin  and  center 
in  the   spinal   bulb.      Other 
fibers    may  cause   the   opposite   effect, 
namely,     dilation,     and    are    therefore 
called  Vaso-dilators.     Examples  of 
these    may   be    found   running    to   the 
arteries  of  the  limbs.      We  have  seen 
that  when  the  muscles  of  any  organ, 

say  the  legs,  act,  they  need  a  greater  supply  of  blood.  Now, 
at  the  same  time  that  nerve  impulses  are  sent  to  the  muscles 
of  the  legs  to  make  the  muscles  shorten,  impulses  are  sent 
along  other  fibers  of  the  same  nerves  to  make  the  arteries 
dilate,  and  allow  more  blood  to  flow  to  these  muscles. 


Lu  rigs— 


Heart 


Liver 


Stomach 


Fig.  35.     Diagrarr  <//  Pneu- 
mogastric  Nerve. 


EFFECTS   OF  ALCOHOL.  93 

The  vaso-constrictor  nerves  and  the  vaso-dilator  nerves 
taken  together  are  called  Vaso-motor  nerves. 

There  is  no  evidence  that  the  sympathetic  ganglia  are 
centers  of  reflex  action. 

Let  us  be  alert  to  discover  the  action  of  these  nerves  as  we 
study  other  parts  of  the  body. 


EFFECTS    OF   ALCOHOL    ON    THE    CIRCULATION. 

"  Alcohol  stimulates  the  heart,  producing  increased  force 
and  rapidity  of  the  cardiac  beat.  It  thus  tends  to  increase  the 
blood-pressure  by  acting  on  the  heart,  and  to  increase  the  flow 
of  blood  from  the  arteries  into  the  veins.  The  effect  on  the 
blood-pressure  is,  however,  partly  counteracted  by  a  coincident 
dilatation  of  the  blood-vessels  of  the  skin,  which  thus  become 
flushed,  and  tends  to  produce  more  sensible  perspiration."  — 
Treatise  on  Hygiene,  STEVENSON  and  MURPHY. 

"  The  warm  and  flushed  condition  of  the  skin  which  fol- 
lows the  drinking  of  alcoholic  fluids  is  probably,  in  a  similar 
manner,  the  result  of  an  inhibition  of  that  part  of  the  vaso- 
motor  center  which  governs  the  cutaneous  arteries."  -—  Text 
Book  of  Physiology,  FOSTER. 

The  control  of  the  muscles  in  the  walls  of  the  arteries  being 
thus  interfered  with,  the  circular  muscles  are  no  longer  made 
to  shorten,  and  the  artery  dilates,  and  receives  more  blood. 

We  may  thus  account  for  the  flushing  of  the  skin  of  the 
face,  which  in  many  individuals  quickly  betrays  indulgence  in 
alcoholic  drink.  If  this  flushing  is  too  often  repeated,  the 
arteries  gradually  "lose  tone,"  and  the  condition  becomes  per- 
manent. The  circulation  in  the  whites  of  the  eyes  may  be 
affected,  making  them  "bloodshot." 

Similar  congestion  occurs  in  the  mucous  membrane  of  the 
stomach  from  the  presence  of  alcohol,  which  may  become  a 


94  THE  BLOOD. 

permanent  inflammation,  followed  in  time  by  very  extensive 
changes  in  appearance  and  function.  It  is  said  that  most  of 
the  alcohol  swallowed  is  absorbed  directly  from  the  stomach, 
and  hence  the  intestines  are  not  so  directly  affected. 

Virchow  says,  "  Alcohol  poisons  the  blood,  arrests  the 
development  of  the  corpuscles,  and  hastens  their  decay." —  "  It 
is  said  to  change  the  form,  lessen  the  number,  and  diminish 
the  size  of  the  corpuscles.  A  degenerate  or  ill-conditioned 
blood,  circulating  in  all  parts  of  the  system,  induces  abnormal 
nutrition.  Abnormal  nutrition  is  always  followed  by  abnormal 
or  perverted  actions,  physical,  mental,  and  moral." — CUTTER. 

The  Blood.  —  To  get  a  drop  of  blood  from  the  finger, 
wind  a  cord  around  the  finger,  beginning  at  the  base,  drawing 
the  cord  moderately  tight,  until  the  last  joint  is  reached.  By 
this  time  the  end  of  the  finger  is  usually  well  distended  with 
blood.  With  a  clean  needle  make  a  quick,  sharp,  light  punc- 
ture near  the  base  of  the  nail ;  this  ordinarily  brings  a  small 
amount  of  blood.  Put  a  small  drop  on  each  of  several  slides 
and  quickly  cover  with  coverslips.  Examine  with  a  high 
power. 

1.  The  Colored  Corpuscles.     These  are  often  called  the  Eed 
Corpuscles.     But  while  in  the  mass  they  give  the  blood  a  red 
appearance,  individually  they  are  faint   yellowish  red.     In 
shape  they  are  seen  to  be  circular  disks,  hollowed  on  each 
side  like  a  sunken  biscuit.     As  they  are  hollowed   on  both 
sides  they  are  more  accurately  described  as  biconcave.     These 
corpuscles  tend   to  gather  side  by  side,  in  rolls,  like  coins. 
They  have  no  nuclei. 

2.  In  the  open  spaces  between  the  rolls  of  colored  corpus- 
cles may  occasionally  be  found  some  of  the  spherical  corpus- 
cles.    They  are  usually  called  the  White  Corpuscles,  but  are 
better  designated  as  the  Colorless  Corpuscles,  since  the  others 
have  only  a  slight  color,  and  these  have  none.     They  usually 


BLOOD   CORPUSCLES. 


95 


have  a  dotted  appearance.     It  is  not  so  easy  to  distinguish 
the  two  kinds  of  corpuscles  as  in  the  case  of  the  frog's  blood 
for  the  two  kinds  are  more  nearly  of  the  same  size  in  the 
human  blood ;  and,  further,  when  the  colored  corpuscles  of 
human  blood  are  seen  flatwise  they  present  a  circular  out- 


White  Corpuscles 


White  Corpuscle 


MODERATELY    MAGNIFIED 

Fig.  36.     Red  and  White  Corpuscles  of  the  Blood. 
| 

line,  while  the  frog's  colored  corpuscles  are  elliptical.  But 
with  a  little  study  the  two  may  be  distinguished.  As  in  the 
frog's  blood,  the  colorless  corpuscles  have  ameboid  movements, 
though  they  are  not  very  marked  unless  the  blood  be  warmed 
to  about  the  temperature  of  the  human  body. 

The  blood  is  composed  of  a  clear  liquid,  the  Plasma,  and 


96  HEMOGLOBIN. 

the  Corpuscles.  In  the  drop  of  blood  examined  under  the 
microscope,  the  Plasma  occupies  the  clear  spaces  between  the 
corpuscles.  The  corpuscles  make  up  one-third  of  the  bulk  of 
the  blood,  and  the  plasma  the  other  two-thirds.  The  plasma 
consists  chiefly  of  water,  having  in  solution  various  salts,  in- 
cluding common  salt;  it  also  contains  the  nourishing  mate- 
rials for  the  tissues.  These  nourishing  materials  have  been 
obtained  from  the  food  by  digestion,  and  consist  chiefly  of 
Proteids,  Fats,  Sugar.  The  plasma  also  contains  waste  mat- 
ters on  their  way  out  of  the  body.  How  the  food  is  prepared 
for  the  building  of  tissue,  and  how  the  waste  matter  is  removed 
from  the  body,  we  shall  study  a  little  later. 

The  difference  in  color  of  an  individual  corpuscle  and  the 
blood  in  the  mass  may  be  better  understood  by  comparing  it 
with  something  that  we  see  more  frequently.  A  tumbler  of 
currant  jelly  has  a  rich,  red  color,  but  a  thin  layer  of  the 
same  jelly,  as  when  one  takes  a  spoonful  on  a  plate,  has  a 
pale  color,  more  yellowish.  The  colorless  plasma  with  the 
colored  bodies  in  it  may  be  compared  to  a  glass  dish  filled 
with  cranberries  and  water. 

The  coloring  matter  in  the  blood,  then,  is  wholly  in  the 
colored  corpuscles.  Examination  of  these  corpuscles  shows 
that  their  color  is  due  to  a  substance  called  Hemoglobin. 
There  is  a  small  amount  of  iron  in  the  hemoglobin,  and  the 
presence  of  this  small  quantity  of  iron  appears  to  be  essential 
to  give  the  blood  its  color.  When  we  come  to  the  study  of 
respiration  we  shall  see  that  the  hemoglobin  in  the  corpuscles 
is  the  chief  agent  in  picking  up  the  oxygen  from  the  air  in 
the  lungs  and  carrying  it  to  the  tissues  in  the  body. 

It  will  be  well  here  to  examine  again  the  flow  of  blood  in 
the  capillaries  of  the  frog's  web.  It  will  be  seen  occasionally 
that  when  one  of  the' colored  corpuscles  is  pressed  against  an 
angle  at  the  forking  of  the  blood  stream,  it  is  sometimes  bent, 


\COAGULATION  OF  BLOOD.  97 

and  that  as  soon  as  the  pressure  is  discontinued  the  corpuscle 
springs  back  to  its  former  shape,  showing  that  it  is  elastic. 

The  Coagulation  of  Blood.  —  When  the  blood  escapes 
from  its  natural  channels  it  usually  changes  from  a  liquid  to 
a  jelly-like  condition.  This  is  known  as  Coagulation.  It  is 
due  to  the  formation  of  the  threads  of  Fibrin  from  the  plasma. 
These  threads  of  fibrin  entangle  and  inclose  the  corpuscles, 
and  the  two  constitute  the  Clot,  or  Coagulum  as  it  is  more 
technically  termed.  The  liquid  that  afterward  separates  from 
the  clot  is  the  Serum,  and  differs  from  the  plasma  only  in  the 
removal  of  the  fibrin,  which  is  exceedingly  small  in  quantity, 
though  of  great  importance  in  its  action.  Many  experiments 
have  been  made,  and  much  has  been  written  about  the  coagu- 
lation of  the  blood,  and  perhaps  its  real  cause  is  not  yet  clear. 
But  we  know  that  the  coagulation  often  serves  to  stop  the 
flow  of  blood  from  wounds,  and  this  is  its  main  use. 

If  freshly  drawn  blood  be  stirred  rapidly  with  a  bundle  of 
wires  (perhaps  the  most  convenient  stirrer  is  made  by  making 
a  little  roll  of  wire  screen),  there  will  soon  collect  on  the  wires 
a  stringy  substance.  Thorough  washing  will  soon  leave  this 
colorless.  It  is  Fibrin.  If  the  stirring  has  been  done  thor- 
oughly the  blood  will  no  longer  clot,  no  matter  how  long  it 
may  stand.  .' '' 

The  following  scheme  shows  the  difference  between  the 
liquid  blood  and  the  coagulated  blood:  — 


f  Plasma  .  .  .  j  Serum 


Liquid  Blood  4                          (Fibrin      [  Ck)fc.          \  Coagulated  Blood. 
^Corpuscles I  J 


Amount  and  Distribution  of  the  Blood.  —  The  blood 
constitutes  about  one-thirteenth  of  the  weight  of  the  body. 
It  is  alkaline  in  reaction,  and  is  a  little  heavier  than  water. 


98  LYMPH.  } 

The  blood  is  divided  among  the  organs  about  as  follows :  — 

1.  One  fourth  is  in  the  heart,  arteries,  and  veins  (including 
those  of  the  lungs). 

2.  One  fourth  in  the  liver. 

3.  One  fourth  in  the  skeletal  muscles. 

4.  One  fourth  in  the  other  organs. 

The  Lymph.  —  We  have  seen  that  the  capillaries  have 
very  thin  walls.  Through  their  walls  part  of  the  plasma  of 
the  blood  soaks  out,  and  is  then  called  Lymph.  It  gets  into 
irregular  cavities  in  the  tissues  called  Lymph  Cavities,  or  Lymph 
Spaces.  Most  of  these  lymph  spaces  are  minute  chinks  or 
crevices  in  the  connective  tissue  of  the  different  parts  of  the 
body.  Opening  out  of  the  lymph  spaces  are  irregular  passage- 
ways called  Lymph  Capillaries,  and  these  lymph  capillaries  are 
continuous  with  thin-walled  tubes  called  Lymph  Vessels  (they 
would  better  be  called  Lymph  Tubes,  for  the  same  reason  that 
we  prefer  the  term  "  blood  tube  "  to  "  blood  vessel,"  because 
the  expression  "  vessel "  is  naturally  misleading).  These 
lymph  tubes  might  be  called  the  Lymph  Veins,  since  they  join 
still  larger  tubes,  closely  set  with  valves,  similar  to  those  of 
the  veins.  But,  unlike  the  blood  veins,  the  lymph  veins  do 
not  gradually  increase  in  size  by  confluence.  They  suddenly 
form  a  large  tube,  the  Receptacle  of  the  Chyle,  beginning  in  the 
upper  part  of  the  abdomen.  This  tube  soon  narrows  and 
passes  through  the  diaphragm,  close  to  the  spinal  column, 
and  up  along  the  column  near  the  aorta,  and  empties  into  the 
veins  of  the  neck  at  the  junction  of  the  left  jugular  and  left 
subclavian  veins.  This  tube  is  the  Thoracic  Duct,  but  would 
better  be  called  the  Lymph  Duct.  It  has  numerous  valves,  and, 
like  some  of  the  smaller  lymph  veins,  it  presents  a  beaded  ap- 
pearance, due  to  the  filling  and  bulging  out  of  the  valves.  In 
the  right  side  of  the  neck  is  a  short  Eight  Lymph  Duct  whith 
receives  lymph  from  the  right  side  of  the  head,  neck,  and 
thorax,  and  from  the  right  arm. 


LYMPH  DUCTS.  99 

In  dissecting  the  frog,  the  looseness  of  the  skin  is  very 
noticeable.  The  large  spaces  under  the  skin  are  lymph 
spaces.  Sometimes  considerable  lymph  is  found  here,  so  that 
in  holding  up  a  frog  the  sagging  of  the  skin  from  the  weight 
of  the  lymph  may  be  easily  seen. 

There  are  valves  where  these  lymph  ducts  empty  into  the 
veins,  which  prevent  any  reflow  of  liquid  into  the  ducts,  but 
allow  the  lymph  to  pass  freely  into  the  veins.  There  are 
plain  muscle  fibers  in  the  walls  of  the  lymph  ducts.  It  will 
now  be  seen  that  while  the  blood  leaves  the  left  ventricle  by 
one  tube,  the  aorta,  it  returns  to  the  right  auricle,  not  merely 
by  the  two  caval  veins,  but  that  a  part  of  the  blood  (i.e.,  of 
the  liquid  part  of  it)  does  not  return  by  blood  veins  at  all,  but 
having  left  the  blood  system  proper  through  the  thin  walls  of 
the  capillaries,  it  is  brought  back  to  the  heart  by  the  lymph 
veins,  which,  however,  join  the  blood  veins  just  before  they 
empty  into  the  heart.  There  is,  in  other  words,  only  one  set 
of  distributing  tubes,  but  there  are  two  sets  of  collecting  or 
returning  tubes.  (See  Fig.  37.) 

In  its  course  the  lymph  passes  through  many  kernel-like 
masses,  the  Lymphatic  Glands.  Lymph  contains  corpuscles 
which  are  considered  identical  with  the  colorless  blood  cor- 
puscles. It  is  thought  that  these  corpuscles  may  be  formed 
in  the  lymphatic  glands. 

The  flow  of  lymph  is  partly  due  to  the  blood  pressure  in  the 
capillaries ;  this  pressure  is  caused  by  the  heart.  (In  the  frog 
there  are  two  small  hearts,  —  not,  however,  near  the  blood- 
pumping  heart,  —  and  these  pump  the  lymph  along.)  In  our 
bodies  the  flow  of  lymph  is  largely  aided  by  any  pressure  that 
may  be  brought  to  bear  on  the  lymph  veins ;  for,  on  account 
of  the  valves,  as  in  the  blood  veins,  any  pressure  must  push 
the  liquid  toward  the  heart.  Thus  the  action  of  the  muscles 
in  the  limbs,  and  in  the  chest  and  abdomen,  the  movements  of 


100 


BLOOD  AND  LYMPH. 


breathing,  and  in  the  bending  of  the  body,  etc.,  all  help  in 
this  flow,  which  is  always,  probably,  very  much  slower  than 
that  in  the  blood  veins. 


Left  Jugular  Vein    — 

Mouth  of 
Lymph  Vein 

LeftSubcIa-^ 
vian  Vein 


-Right  Lymph  Vein 


Right  Subclavian 
Vein 


Precaval  Vein 


Postcaval  Vein 


Main  Lymph  Vein 
(Thoracic  Duct) 


Lymph  Capillaries 


••  Blood  Capillaries 


Fig.  37.    Diagram  of  the  Circulation  of  Blood  and  Lymph.    (Dorsal  View.) 


BLOOD  AND   LYMPH. 


101 


Lymph 


Capillary. 


Lymph  is  a  clear  liquid.  (Chyle  and  the  lacteals  will  be 
considered  when  we  study  digestion.)  It  is  more  watery  than 
the  blood  plasma,  but  contains  a  share  of  all  its  nutritious 
substances.  Lymph  may.  be  denned  as  diluted  blood  minus 
red  corpuscles.  The  blood  proper  never  reaches  the  tissues. 
The  cells  of  the  tissues  are  bathed  in  the  lymph  which  fills 
the  spaces  in  the  connective  tissue  (and  we  have  seen  that  the 
connective  tissue  pervades  nearly  all  the  tissues  of  the  body), 

as  water  may  fill  the  spaces 
left  between  stones  built  in- 
to a  wall.  The  cells  get  all 
their  nourishment  from  the 
lymph,  and  into  the  lymph 
they  throw  all  their  waste 
matter.  Each  cell  may  be 
compared  to  an  individual 
ameba,  which  lives  in  water, 
and  takes  all  its  nourish- 
ment from  that  water,  and 
throws  all  its  waste  product 
into  the  same  water.  As 
water  is  the  medium  ir 
which  the  ameba  lives,  so 
we  may  say  lymph  is  the 
medium  in  which  the  cells 
of  the  body  live. 

The    cells   of   the   body, 
i.e.,  all  the  active,  working 

cells,  may,  therefore,  be  said  to  live  an  aquatic  life,  and  only 
dead  cells,  as  of  hair,  epidermis,  etc.,  are  in  air.  We  might 
also  say  that  not  only  the  human  body,  but  all  animal  life, 
is  aquatic. 

We  can  see  that  the  movement  and  renewal  of  the  lymph 


Oxygen - — 


Food 


Other 
Wastes 


Fig.  38.    Relation  of  Blood  and  Muscle. 
(Lymph  being  middleman.) 


102  THE  SPLEEN. 

is  as  necessary  as  the  circulation  of  the  blood  itself ;  is,  in 
fact,  the  most  important  part  of  it. 

We  have  noticed  the  pericardia!  liquid.  There  is  also  a 
small  quantity  of  similar  liquid  around  the  lungs  in  the  pleu- 
ral  cavities,  and  in  the  abdominal  or  Peritoneal  Cavity,  around 
the  digestive  organs  ;  also  in  the  cavities  of  the  brain.  The 
liquid  in  each  case  is  lymph ;  and  these  cavities,  often  called 
Serous  Cavities,  are  Lymph  Cavities.  They  communicate  with 
the  lymph  tubes.  In  health  the  amount  of  the  liquid  in  these 
cavities  is  small,  but  in  certain  disorders  it  may  accumulate. 
In  general,  such  affections  are  called  "  dropsy."  The  lymph 
may  also  accumulate  in  the  tissues  of  the  extremities,  causing 
swelling  of  the  limbs. 

It  is  evident  that  the  materials  needed  by  the  cells  of  the 
different  tissues  are  not  the  same.  So,  as  one  tissue  takes 
certain  materials  and  another  tissue  others,  it  is  clear  that 
the  lymph  will  n-ot  be  of  quite  the  same  composition  in  the 
different  parts  of  the  body.  This  difference  is  further  due  to 
the  difference  in  the  waste  products  thrown  out  by  the  differ- 
ent cells.  Hence  the  composition  of  the  blood  varies  con- 
siderably in  different  regions.  But  the  lymph  from  all  the 
tissues  unites  with  the  blood  from  all  the  tissues  in  the  right 
heart,  and  on  their  way  to  it  in  the  larger  veins.  So  the  con- 
stant slight  differences  in  composition  of  the  blood  and  lymph 
in  the  various  tissues  are  counterbalanced  by  the  mingling  of 
the  currents  from  these  various  parts  in  the  large  streams  to 
and  from  the  heart  that  we  call  the  arteries  and  veins. 

The  Spleen.  —  The  function,  or  functions,  of  the  spleen 
are  not  well  understood.  It  is  believed  to  have  something  to 
do  with  the  renovation  of  the  blood,  perhaps  forming  colorless 
corpuscles  and  destroying  colored  corpuscles.  At  any  rate, 
the  physiologists  generally  call  it  a  blood  gland.  It  is  unlike 
true  glands  in  that  it  has  no  duct,  and  forms  no  secretion  to 


MASSAGE.  103 

be  poured  into  any  cavity,  like  the  glands  of  excretion  and 
secretion.  It  has  been  found,  in  the  case  of  accidents  to  man. 
and  by  experiment  011  the  lower  animals,  that  life  may  con- 
tinue after  this  organ  has  been  removed. 

Massage.  —  A  system  of  pressing,  rubbing,  and  kneading 
the  muscles  is  known  as  massage.  It  helps  the  flow  of  the 
blood  and  lymph,  thus  aiding  in  washing  out  the  waste  prod- 
ucts from  the  muscles  and  other  parts  of  the  body  that  are  to 
be  reached  by  pressure.  We  have  seen  that  one  of  the  bene- 
fits of  exercise  is  to  promote  the  circulation  of  the  blood  and 
of  the  lymph,  and  so  to  help  get  rid  of  the  waste  matters  that 
are  produced  by  the  activity  of  the  various  organs.  Many  in- 
valids cannot  take  active  exercise.  So  this  passive  exercise 
may  very  fairly  take  its  place,  and  assist  in  the  nutrition  of 
the  tissues  by  accelerating  the  flow  of  blood  and  lymph,  bring- 
ing new  nourishment  and  carrying  away  wastes.  For  students 
who  do  not  take  sufficient  exercise  it  is  a  good  thing  to  rub 
the  body  thoroughly  and  briskly,  not  only  after  a  bath,  but 
often  with  the  hands  or  with  a  dry  towel. 

Transfusion  of  Blood. — Transfusion  of  blood  is  the  trans- 
fer of  blood  from  the  blood-vessels  of  one  animal  to  those  of 
another.  Transfusion  may  be  direct  or  immediate,  as  when 
the  blood-vessels  of  the  two  animals  are  connected  by  tubing, 
so  that  the  blood  passes  from  one  to  the  other  without  expo- 
sure to  the  air ;  in  indirect  or  mediate  transfusion,  the  blood  is 
first  drawn  into  a  receptacle.  In  indirect  tranfusion,  the  blood 
is  often  defibrinated  before  transference.  The  blood  may  be 
introduced  either  into  an  artery  or  a  vein ;  if  into  a  vein,  it  is 
sent  in  the  direction  of  the  natural  flow,  i.e.,  toward  the  heart ; 
if  into  an  artery,  in  either  direction.  Soon  after  the  discovery 
of  the  circulation  of  the  blood,  the  operation  of  transfusion 
began  to  be  practiced,  and  high  hopes  were  indulged  in  as  to 
its  value.  But  it  was  soon  found  to  be  attended  by  so  much 


104  TRANSFUSION   OF  BLOOD. 

danger  that  it  is  now  seldom  used.  It  is  resorted  to  (1)  after 
great  loss  of  blood ;  (2),  after  some  forms  of  poisoning,  part 
of  the  blood  is  withdrawn  and  replaced  by  fresh  blood ;  and 
(3),  in  certain  disordered  conditions  of  the  blood.  The  chief 
dangers  are,  (1),  the  introduction  of  air,  which  forms  minute 
bubbles,  and  stops  the  blood-flow  in  the  capillaries ;  (2),  the 
introduction  sometimes  causes  coagulation  within  the  blood- 
vessels, and  (3),  the  serum  of  the  introduced  blood  sometimes 
destroys  the  corpuscles  of  the  blood  to  which  it  is  added.  In 
the  earlier  practice,  lamb's  blood  was  employed ;  but  now, 
when  transfusion  is  practiced  on  man,  only  human  blood  is 
used.  It  has  been  found  safer  and  better,  after  great  loss  of 
blood  from  hemorrhage,  to  introduce  a  salt  solution  of  about 
the  natural  degree  of  saltness  of  the  blood ;  this  restores  the 
normal  volume  of  circulating  liquid,  and  avoids  most  of  the 
dangers  except  that  of  introducing  air.  The  numerous  fatal 
results  of  this  operation  have  shown  that  it  should  not  be 
resorted  to  except  in  cases  of  extreme  necessity. 

For  directions  about  stopping  the  flow  of  blood  from 
wounds  see  chapter  XI.  and  the  books  named  below. 

What  other  process  keeps  pace  with  the  coursing  of  the 
blood  through  the  body,  being  its  running  mate,  so  to  speak  ? 

READING.  —  Prompt  Aid  to  the  Injured,  Doty  ;  Emergencies, 
Dulles ;  Emergencies,  Howe ;  first  Aid  to  the  Injured, 
Lawless ;  first  Aid  to  the  Injured,  Morton ;  first  Aid 
in  Illness  and  Injury,  Pilcher ;  Sickness  and  Accidents, 
Curran. 


OHAPTEE    V. 


RESPIRATION. 

Is  it  not  a  very  striking  fact  that  we  take  one  breath  for 
every  four  heart-beats  ?  That  whatever  quickens  the  breath- 
ing also  quickens  the  heart,  so  that  the  two  always  keep  in 
almost  the  same  ratio  ?  Let  us  learn  what  are  the  many  inti- 
mate relations  of  the  blood  pump  and  the  air  pump,  the  blood 
system  and  the  air  system,  of  Circulation  and  Respiration. 

The    Organs    of 
Respiration  are  :  — 

1.  The  Lungs    and 
Air  Tubes. 

2.  The  structures 
which  increase  and  di- 
minish the  size  of  the 
chest,    principally 
the  diaphragm,  and 
the  muscles  acting 

011  the  ribs. 

The   lungs   con- 
sist of :  — 

1.  An  immense 
number   of    small 
sacs,  the  Air   Ves- 
icles,   which   com- 
municate with  the 

outer  air  by  the  Bronchial  Twigs,  Bronchi,  and  Trachea. 

2.  ThQ   Pulmonary   Capillaries,  forming   a  thick   network 

105 


Fig.  39.     The  Trachea  and  Bronchial  Tubes,  Showing 
Two  Clusters  (Alveoli)  of  Air  Vesicles. 


106 


ORGANS   OF  THE   THORAX. 


around  and  between  the  air  sacs.  These  capillaries  receive 
their  blood  from  the  pulmonary  artery,  and  return  it  to  the 
heart  by  the  pulmonary  veins. 


1.  Pulmonary  Orifice 

2.  Aortic  Orifice 


3.  Left  Auriculo-Ventricular  Orifice 

4.  Right  Auriculo-Ventricular  Orifice 


Fig.  40.    Front  View  of  the  Thorax.     The  Ribs  and  Sternum  are  Represented  in 
Relation  to  the  Lungs,  Heart,  and  other  Internal  Organs. 


CILIATED    CELLS. 


107 


Cilia 


Cell  — 


The  air  vesicles,  with  their  supplying  air  tubes  and  their 
surrounding  blood  tubes,  are  bound  together  by  elastic  tissue, 
which  fills  up  most  of  the  intervening  space. 

The  windpipe  has  in  its  walls  C-shaped  cartilages,  with  the 
open  part  of  the  C  on  the  dorsal  surface.  These  cartilages 
continue  in  the  bronchi,  and  so  on  until  in  the  smaller  twigs 
they  finally  disappear. 

The  cartilages  are  held  together,  and  the  dorsal  gap  of  the 
cartilages  (the  gap  would  be  like  that  of  a  series  of  horse- 
shoes piled  on  top  of  each  other)  bridged,  by  tough  fibrous 
tissue,  with  much  elastic  tissue,  and  with  plain  muscle  fibers ; 
these  last-mentioned  structures  are  very  abundant  in  the 
smaller  air  tubes. 

The  lining  of 
the  trachea  is  a 
Mucous  Membrane. 
It  pours  out  on 
its  surface  a  sub- 
stance somewhat 
like  white-of-egg, 
called  Mucus. 
This  keeps  the 

air  moist,  and  catches  particles  of  dust,  etc.,  that  are  in  the 
inspired  air.  There  is  a  constant  slow  current  of  mucus 
toward  the  throat,  whence  it  is,  from  time  to  time,  hawked  up. 
This  current  of  mucus  is  caused  by  the  Cilia  projecting  from 
the  lining  cells  of  tin  trachea.  They  are  little  hairlike  pro- 
jections, in  countless  numbers,  like  a  field  of  grass,  each  stalk 
having  the  power  of  bending  back  and  forth,  making  a  quick 
stroke  toward  the  throat,  then  a  slower  recover  stroke.  Thus 
the  united  wavelike  action  of  the  myriads  of  lashing  cilia 
paddles  the  mucus  headward.  (See  page  388.) 

All  the  cavities  and  passages  in  the  body  to  which  the  air 


Nucleus 


Fig.  41.    Ciliated  Cells  Lining  the  Air  Tubes. 


108 


LUNGS  AND  PLEURA. 


Trachea 


Pleural  Space  -  - •  - 
(Exaggerated) 


Chest  Wall- -- 


—•=*-  Pleura 


has  access,  such  as  the  digestive  and  respiratory  passages,  etc., 
are  lined  by  mucous  membrane  (not  all  ciliated). 

The  outside  of  each  lung  is  covered  by  a  thin  adherent 
membrane,  the  pleura,  which 
completely  invests  it,  except 
at  the  root  of  tiie  lung, 
where  the  bronchus  and 
blood  tubes  en- 
ter. Here  the 
pleura  turns 
toward  and 
adheres  'to  the 
inner  wall  of 
the  chest,  form- 
ing its  lining  (still  called 
the  pleura),  and  below 
passes  over  the  anterior 
surface  of  the  diaphragm. 
The  lung  is  thus  free,  ex- 
cept at  its  root,  where  the  air  and  blood  tubes  enter.  A  very 
small  quantity  of  liquid  moistens  the  contiguous  surfaces  of 
the  pleurae  on  the  outside  of  the  lung  and  the  inside  of  the 
chest  wall,  so  they  move  easily  one  upon  the  ether  during 
respiration.  As  the  lungs  are  always  distended  enough  to 
fill  the  chest  cavity,  these  two  surfaces  are  always  in  con- 
tact. In  pleurisy  (inflammation  of  the  pleurae),  pain  is  felt 
in  breathing  from  friction  or  adhesion  of  these  surfaces. 

In  studying  respiration,  let  us  constantly  keep  in  mind 
these  facts  :  — 

1.  The  lungs  are  highly  elastic,  and 

2.  Highly  porous,  each  air  vesicle  being  in  direct  commu- 
nication with  the  outer  air  by  means  of :  — 

3.  Air  tubes  that  always  stand  open, 


Fig.  42.     Diagram  of  the  Lungs  and  Pleurae. 


MOVEMENTS    OF  RESPIRATION.  109 

4.  And  are  always  moist  internally. 

5.  The  pulmonary  capillaries  closely  invest  each  air  vesicle. 

6.  The  lungs  are  always  expanded  enough  to  fill  all  the 
space  in  the  chest  not  occupied  by  other  organs,  and 

7.  Freely  movable,  except  at  the  place  of  entrance  of  the 
bronchi  and  blood  tubes. 

8.  The  smooth,  moist  pleurae. 

The  diaphragm  is  a  thin  muscle  making  a  complete  parti- 
tion between  the  abdominal  cavity  and  the  chest  cavity.  It 
is  convex  anteriorly,  concave  posteriorly ;  its  ventral  border 
is  attached  to  the  inside  of  the  chest  wall  about  opposite  the 
lower  end  of  the  breast-bone,  thence  obliquely  along  the  bor- 
der of  the  ribs  (as  felt  in  front),  and  the  dorsal  attachment  is 
posterior  to  the  ventral  attachment.  Its  general  position  is 
shown  in  the  ventral  and  lateral  views,  showing  the  action 
of  the  diaphragm  and  chest  wall  during  inspiration  and  ex- 
piration. (See  Figs.  40,  42,  and  45.) 


APPARATUS   ILLUSTRATING   THE    MOVEMENTS    OF 
RESPIRATION. 

To  Show  the  Action  of  the  Diaphragm  and  Lungs.  — 
MATERIAL.  —  Bell  jar  with  stopper,  sheet  of  rubber  large 
enough  to  cover  the  mouth  of  the  jar,  toy  rubber  balloon, 
cork  (rubber  preferred),  glass  tube,  strong  rubber  band  (such 
as  boys  use  for  slung-shots),  marble. 

PREPARATION.  —  Lay  the  marble  on  the  center  of  the  sheet 
of  rubber,  double  the  rubber  over  it,  stretching  the  rubber 
strongly  over  the  marble,  and  tie  the  marble  firmly  in  its 
place.  Stretch  the  sheet  of  rubber  over  the  mouth  of  the  jar, 
with  the  projection  made  by  the  marble  on  the  outside,  and 
fasten  with  rubber  band.  Bore  a  hole  in  the  cork,  and  fix  the 
glass  tube  snugly  in  it,  so  that  the  lower  end  of  the  tube  will 


110 


CROSS-SECTION   OF  THORAX. 


extend  about  half-way  down  the  jar.     Tie  the  balloon  on  the 
lower  end  of  the  glass  tube. 

EXPERIMENT    1.  —  Inflate  the  balloon.     Consider  that   it 
requires  some  expenditure  of  energy  to  do  this.     When  the 


Triangularis  Sterni 
Internal   Mammary  Vessels 


Pleura 
Pulmonalis 


Lett  Phrenic 
Nerve 


ura  Costalii 


(  Sympathetic  Nerve 
Mediastinum  < 

(  Thoracic  Duct 


Pneumogastric  Nerves 


Posterior 


Fig.  43.     A  Transverse  Section  of  the  Thorax,  Showing  the  Relative  Position  of  the 
Viscera  and  Reflections  of  the  Pleurae. 


mouth  is  taken  away  from  the  tube  the  balloon  immediately 
collapses. 

EXPERIMENT  2.  —  Insert  the  balloon  and  tube  into  the  jar, 
but  do  not  cork,  and  repeat  Experiment  1.     The  same  results 


MECHANICS   OF  RESPIRATION.  Ill 

as  before  are  noticed,  and  it  will  further  be  seen,  or  rather 
heard  and  felt,  that  when  the  balloon  is  inflated,  some  air 
comes  out  of  the  jar  around  the  tube,  and  when  the  balloon 
collapses  air  again  enters  the  jar. 

EXPERIMENT  3.  —  Again  inflate  the  balloon,  and  while  it  is 
inflated  tightly  cork  the  jar.  If  all  the  parts  fit  well,  the  bal- 
loon should  now  remain  inflated.  This  may  at  first  seem 
strange,  as  the  mouth  is  taken  away  from  the  tube,  and  the 
tube  left  entirely  open  to  the  air.  But  it  will  be  seen  that  to 
just  the  extent  that  the  balloon  contracts,  so  much  more  space 
is  left  in  the  jar  outside  the  balloon.  This  means  dimin- 
ished pressure ;  and  the  pressure  of  the  outer  air  presses  the 
diaphragm  up,  and  keeps  the  balloon  partly  distended,  main- 
taining equilibrium. 

EXPERIMENT  4.  —  Pull  the  diaphragm  down,  using  the 
marble  as  a  handle.  This  shows  the  expansion  of  the  lung 
by  the  pressure  of  the  external  air  when  more  space  is  given 
by  the  depression  of  the  diaphragm.  On  releasing  the  dia- 
phragm, it  springs  upward,  and  the  balloon  becomes  reduced 
in  size,  driving  out  part  of  the  air  that  was  in  it.  This  shows 
how  expiration  is  accomplished,  so  far  as  the  diaphragm  is 
concerned. 

If  a  bell  jar  be  not  at  hand,  a  quart  bottle  may  be  used, 
after  cutting  off  the  bottom,  as  follows  :  File  a  deep  notch 
across  near  the  bottom ;  heat  an  iron  rod,  and  apply  the  end 
of  it  to  one  end  of  the  notch,  and  slowly  draw  the  rod  around 
to  the  other  end  of  the  notch  (the  rod  may  need  to  be  re- 
heated). After  cracking  off  the  bottom  of  the  jar,  file  the 
edges  so  they  will  not  cut  the  rubber. 

Let  each  pupil  make  a  drawing,  showing  the  position  of 
the  parts  in  Inspiration  and  in  Expiration. 

Action  of  the  Walls  of  the  Chest.  —  To  show  the  ac- 
tion of  the  chest  walls,  take  a  pair  of  bellows,  and  stop  the 


112  MINUTE  STRUCTURE  OF  LUNG. 

hole  in  the  side.  Now,  when  the  handles  are  separated,  air 
enters  the  nozzle,  and  when  the  handles  are  brought  together 
air  is  driven  out.  If  a  rubber  balloon  be  tied  to  a  glass  tube 
tightly  corked  in  the  nozzle  of  the  bellows,  and  then  the  bel- 
lows are  Avorked,  air  will  enter  and  innate  the  balloon  when 
the  handles  are  separated,  and  air  will  rush  out  when  the 
handles  are  brought  together.  If  the  sides  of  the  bellows 
have  a  tight  window,  the  changes  in  the  balloon  can  be  seen. 

To  illustrate  the  minute  anatomy  of  the  lung,  take  a  rubber 
balloon,  a  glass  tube,  two  rubber  tubes,  one  dyed  red,  the  other 
blue,  a  bag  of  netting,  with  one  side  dyed  red  and  the  other 


....BRONCHIAL  TUBE. 

VEIN I 


Fig.  44.    Minute  Structure  of  the  Lungs,  Showing  Air  Vesicles  and 
Capillaries. 

side  blue.  Tie  the  balloon  011  the  end  of  the  glass  tube,  slip 
the  bag  of  netting  over  the  balloon,  and  tie  it,  with  the  ends  of 
the  rubber  tubes  on  the  corresponding  sides  of  the  bag.  Slip 
a  short  piece  of  the  rubber  tube  on  the  end  of  the  glass  tube, 
and  when  the  balloon  is  inflated  shut  the  air  in  by  means  of  a 
pinchcock.  The  balloon  represents  an  air  vesicle,  the  glass 


MOVEMENTS   OF  RESPIRATION.  113 

tube  a  bronchial  twig,  the  blue  tube  a  subdivision  of  the  pul- 
monary artery,  the  netting  the  capillaries  around  the  vesicle, 
and  the  red  tube  one  of  the  branches  of  the  pulmonary  veins. 

That  the  lungs  do  not  collapse  after  death  may  be  shown 
in  a  cat  or  rabbit.  Open  the  abdominal  cavity,  and  pull  back 
the  liver  and  stomach.  The  pink  lungs  may  be  seen  through 
the  thin  diaphragm.  Pull  the  diaphragm  back  to  see  that  the 
lungs  follow  it,  keeping  in  contact  with  it  all  the  time.  Now 
lightly  puncture  the  diaphragm  on  one  side.  The  lung  on 
this  side  collapses,  but  the  lung  of  the  other  side  remains  ex- 
panded, showing  that  the  two  pleural  cavities  are  separate. 

The  Movements  of  Respiration.  —  The  process  of  res- 
piration consists  of  two  acts,  inspiration  and  expiration.  In 
inspiration  the  principal  active  forces  in  the  body  are,  first,  the 
diaphragm ;  and  second,  the  muscles  which  elevate  the  ribs. 

The  diaphragm  is  a  muscle,  and  when  its  fibers  shorten, 
the  diaphragm  is  pulled  down.  In  moving  down  it  presses  on 
the  abdominal  organs,  and  makes  the  abdomen  protrude  later- 
ally and  ventrally.  This  lowering  of  the  diaphragm  increases 
the  space  in  the  chest ;  the  air  already  in  the  chest  expands 
to  fill  this  greater  space.  When  expanded  it  exerts  less  pres- 
sure than  before,  and  the  air  outside,  having  greater  pressure, 
enters  till  equilibrium  is  produced.  The  air  enters  through 
the  trachea,  presses  on  the  inside  of  the  elastic  lungs,  and 
makes  their  bases 'extend,  following  the  diaphragm  in  its  de- 
scent. The  bases  of  the  lungs  remain  in  contact  with  the 
upper  surface  of  the  diaphragm  all  the  time. 

Certain  muscles  of  the  chest  wall  elevate  the  ribs  and  ster- 
num. This  act  widens  the  chest;  and  the  air,  as  before, 
presses  in  through  the  open  trachea,  and  keeps  the  sides  of 
the  lungs  in  contact  with  the  inner  surfaces  of  the  chest 
walls. 

Inspiration  requires  considerable   effort,  because   the  dia- 


114  INSPIRATION  AND  EXPIRATION. 

phragin  in  its  descent  presses  upon  the  elastic  organs  of  the 
abdomen  (stomach,  liver,  etc.),  and  these  organs,  in  turn,  are 
pressed  against  the  elastic  walls  of  the  abdomen.  It  is  some- 
what as  if  one  pressed  a  pillow  down  into  a  rubber  bag ;  the 


Increased  Air  Space. 


Inspiration  Expiration 

Fig.  45.     Diagrammatic  Sections  of  the  Body  in  Inspiration  and  Expiration. 

pillow  would  spring  up  as  soon  as  the  pressure  was  stopped, 
because  of  its  own  elasticity  as  well  as  that  of  the  bag. 
Therefore,  as  soon  as  the  diaphragm  relaxes,  the  elastic  walls 
of  the  abdomen  retreat,  and  the  abdominal  organs  rise  to  their 
former  place. 

When  the  ribs  are  elevated,  the  cartilages  which  connect 
the  ventral  ends  of  the  bony  parts  of  the  ribs  with  the  breast- 
bone are  slightly  bent.  When  the  muscles  relax,  the  elasti- 
city of  the  rib  cartilages  helps  to  bring  the  ribs  back  to  their 
former  position,  thus  reducing  the  chest  to  its  former  width. 


INSPIRATION  AND   EXPIRATION.  115 

Thus  we  see  why  expiration  is  easy ;  in  fact,  "  does  itself  " 
(in  ordinary  respiration),  by  the  elastic  reactions  mentioned. 
But  inspiration  is  harder  than  it  would  be  if  it  were  not  for 
the  fact  that  the  descent  of  the  diaphragm  meets  resistance, 
and  the  ribs,  in  rising,  have  to  overcome  resistance  in  bending 
the  costal  cartilages,  and  in  raising  the  weight  of  the  chest 
walls  and  shoulders. 

When  one  opens  a  door  that  has  a  spring  to  shut  it,  he 
has  to  expend  more  energy  to  open  the  door  than  he  would 
if  he  did  not  have  to  bend  (twist  or  compress)  the  spring  at 
the  same  time.  But  no  effort  is  needed  to  shut  the  door. 
The  door  was  opened  and  shut  at  the  same  time ;  i.e.,  when  the 
door  was  opened,  force  was  stored  in  the  spring  (in  the  form 
of  what  is  called  potential  energy),  and  this  stored  energy 
shuts  the  door  while  we  pass  on.  We  can  better  afford  to 
employ  more  energy  while  opening  the  door,  than  to  take  the 
extra  time  to  shut  it.  If,  then,  a  door  with  such  spring  were 
fastened  open,  it  might  remain  open  for  a  long  time.  When 
released  it  flies  shut.  If  one,  in  this  case,  asks,  "Who  shut 
the  door  ?  "  the  answer  is,  "  The  person  who  opened  it." 

So  in  the  act  of  inspiration  we  perform  a  double  work  in 
storing  energy  by  which  the  expiration  is  performed  without 
active  muscular  effort. 

Reviewing  these  points  we  have  :  — 

FORCES    OF    INSPIRATION. 

1.  Depression  of  the  diaphragm. 

2.  Muscles  elevating  the  ribs. 

3.  Pressure  of  the  external  air. 

RESISTANCES    TO    INSPIRATION. 

1.  Compression  of  the  abdominal  organs,  and  stretching 
abdominal  walls. 


116  MODIFICATION   OF  RESPIRATION. 

2.  Bending  the  rib  cartilages,  and  lifting  the  chest. 

3.  Stretching  the  lungs. 

ELASTIC    REACTIONS    OF    EXPIRATION. 

1.    Elastic  reaction  of  the  abdominal  walls  and  contents. 
.  2.    Elastic  reaction  of  the  rib  cartilages. 

3.    Elastic  reaction  of  the  lungs. 

Thus  far  we  have  been  speaking  of  ordinary  respiration. 
In  forced  respiration,  as  in  shouting,  many  muscles  are  brought 
into  play  to  expel  the  air  rapidly  and  forcibly.  In  such  an 
act  as  coughing  there  is  vigorous  action  of  the  abdominal 
muscles. 

The  main  part  of  respiration  is  performed  by  the  dia- 
phragm ;  and  the  more  common  mode  of  respiration  is  there- 
fore called  abdominal,  or  diaphragmatic,  respiration.  In  women 
of  the  civilized  races,  respiration  is  more  largely  accomplished 
by  the  action  of  the  thoracic  muscles,  and  is  called  thoracic, 
or  costal,  respiration.  In  children  the  respiration  is  of  the 
abdominal  type. 

Ordinary  inspiration  takes  slightly  less  time  than  expira- 
tion. 

The  rate  of  respiration  in  the  adult  varies  from  sixteen  to 
twenty-four  per  minute,  the  average  being  about  seventeen 
times  a  minute ;  about  one  respiration  for  every  four  heart- 
beats. Light  is  favorable  to  respiratory  activity. 

The  rate  is  affected. by  the  position  of  the  body,  state  of 
activity,  temperature,  digestion,  emotions,  age,  disease,  etc. 

Coughing  is  a  forcible  expiration,  usually  directed  through 
the  mouth,  and  for  the  purpose  of  getting  rid  of  some  foreign 
substance,  or  caused  by  irritation.  In  sneezing  there  is  first 
a  deep  inspiration,  and  then  the  current  of  air  is  forced  out, 
chiefly  through  the  nose.  Sneezing  may  be  prevented  by 
pressing  firmly  on  the  upper  lip.  Crying,  laughing,  sobbing, 


LUNG    CAPACITY.  117 

are  modifications  of  respiration  connected  with  certain  emo- 
tions. Yawning  and  sighing  are  deeper  breathings,  caused 
by  ennui,  depressing  emotions,  or  a  deficient  ventilation.  Hic- 
cuping  is  sudden  inspiration,  produced  by  spasmodic  action 
of  the  diaphragm,  accompanied  by  sudden  closure  of  the 
glottis,  and  is  often  caused  by  some  disorder  of  stomach 
digestion.  Snoring  is  caused  by  breathing  through  the  mouth, 
and  setting  the  soft  palate  into  vibration.  Sniffing  is  sudden 
inspiration :  the  diaphragm  is  suddenly  pulled  down,  the  air 
in  the  nasal  cavity  is  thus  drawn  downward,  and  the  air  we 
wish  to  test,  or  the  odor  we  wish  to  inhale,  is  thus  drawn  into 
the  upper  nasal  cavities  ;  whereas  in  ordinary  inspiration  most 
of  the  air  passes  along  the  lower  part  of  the  nasal  passage. 
In  hawking,  the  air  is  forced  out  through  the  narrowed  pas- 
sage between  the  root  of  the  tongue  and  the  soft  palate  to 
remove  mucus.  Gargling  is  forcing  air  up  through  liquid 
held  between  the  tongue  and  the  soft  palate. 

Capacity  of  the  Lungs.  —  Have  the  class  stand,  and  each 
pupil  hold  up  his  right  hand. 

1.  Let  all  breathe  together,  at  the  ordinary  rate  and  depth, 
and  let  the  hand  rise  about  three  inches  during  inspiration, 
and  fall  again  during  expiration.     The  amount  of  air  taken 
in  at  an  ordinary  breath  is  from  20  to  30  cubic  inches,  or 
about  a  pint.     This  is  called  the  Tidal  Air. 

2.  As  before,  let  the  hand  go  up  and  down  with  the  breath- 
ing, but  at  the  end  of  the  third  inspiration,  instead  of  stopping 
with  the  usual  amount,  keep  on  breathing  in  as  much  as  pos- 
sible, letting  the  hand  rise  accordingly.     This  air  that  can  be 
taken  in  above  the  ordinary  breath  is  called  the  Complemental 
Air,  and  it  is  estimated  to  be,  on  the  average,  about  120  cubic 
inches. 

3.  Begin  as  before,  and  at  what  would  be  the  end  of  the 
third  expiration  continue  to  drive  out  as  much  air  as  possible, 


118  LUNG   CAPACITY. 

indicating  the  degree  by  correspondingly  lowering  the  hand. 
This  air  that  can  be  breathed  out  beyond  the  ordinary  expira- 


COMPLEMENTAL  AIR. 

120  CUBIC  INCHES. 
AIR  THAT  CAN  BE,   BUT  SELDOM  IS,    TAKEN  IN. 


TIDAL  AIR.  —  20  to  30  Cubic  Inches  Air.      Taken  In 
and  Sent  Out  at  Each   Breath. 


RESERVE  AIR.  ^ 

C5j 

I 

100  CUBIC  INCHES. 

AIR  THAT  CAN  BE,   BUT  SELDOM  IS,   DRIVEN  OUT. 


RESIDUAL  AIR. 

100  CUBIC  INCHES. 
AIR  THAT  CANNOT  BE  DRIVEN  OUT. 


f 


Fig.  46.     Diagram  of  Lung  Capacity. 

tion  is  called  the  Reserve  Air,  and  is  reckoned  at  about  100 
cubic  inches. 


LUNG   CAPACITY.  119 

4.  The  air  cannot  all  be  breathed  out.  The  remainder  is 
called  the  Residual  Air,  and  is  computed  to  be  about  100  cubic 
inches. 

All  the  air  that  can  be  breathed  out  after  a  full  inspira- 
tion, i.e.,  the  sum  of  the  complemental,  tidal,  and  reserve  air, 
would  be  about  240  to  250  cubic  inches,  and  is  called  the 
Vital  Capacity. 

Of  course  these  figures  represent  only  the  average  of  cer- 
tain experiments  and  observations.  By  practice  any  one  can 
considerably  increase  his  vital  capacity. 

A  simple  method  of  measuring  these  stages  of  respiration 
is  to  graduate  a  gallon  bottle  carefully  to  pints  by  pouring  in 
water  and  marking  on  the  outside  with  a  file.  Then  invert 
the  bottle  in  a  trough  of  water,  and  inhale  from  it  by  means 
of  a  rubber  tube.  Or  fill  the  bottle,  invert  in  water,  and 
exhale  into  it. 

It  will  be  observed,  since  the  same  tube  that  takes  in  the 
fresh  air  also  sends  out  the  bad  air,  that  when  the  current  is 
reversed  the  first  air  to  be  sent  out  is  the  last  air  that  came 
in,  which  is,  therefore,  the  best  air  in  the  lungs.  But  the 
amount  taken  at  each  inspiration  is  three  or  four  times  as 
great  as  the  capacity  of  the  trachea  and  bronchi,  so  that  at 
each  breath  two-thirds  or  more  of  the  fresh  air  is  taken 
directly  into  the  air  vesicles.  In  addition  to  this  the  better 
air  in  the  trachea  is  mixing  with  the  poorer  air  in  the  air 
vesicles  by  diffusion ;  the  oxygen  being  more  abundant  in  the 
trachea,  passes  down  into  the  deeper  parts  of  the  lung,  while 
the  carbon  dioxid,  so  abundant  in  the  vesicles,  passes  up  into 
the  trachea. 

At  each  inspiration  the  air  in  the  lungs  receives  about  one- 
eighth  of  its  volume  of  fresh  air,  and  at  each  expiration  about 
one-ninth  of  the  air  is  sent  out.  But  it  must  be  remembered 
that  this  one-ninth  sent  out  is  not  the  worst,  but  the  very  best, 


120  HYGIENE  OF  BREATHING. 

air  that  is  in  the  lungs,  which  has  lately  entered  the  air  tubes, 
and  part  of  which  can  only  by  diffusion  reach  the  air  vesicles, 
where  the  exchanges  are  taking  place  between  the  air  and  the 
blood. 

Hygiene  of  Breathing.  —  If  one  had  a  barrel  of  water 
with  a  lot  of  mud  in  the  bottom,  and  something  kept  stirring 
up  the  mud,  of  course  the  water  would  be  muddiest  near  the 
bottom.  Now,  suppose  a  cupful  of  the  water  from  the  top 
were  dipped  out  and  thrown  away,  and  a  cup  of  pure  water 
were  poured  in.  This  method  of  renewing  the  water  would 
be  like  the  renewal  of  the  air  in  the  lungs,  in  that  the  least 
bad  material  is  removed,  while  the  addition  of  fresh  supply 
is  made  at  the  point  where  the  material  is  least  vitiated.  We 
see  that  here  we  might  help  matters  by  dipping  faster,  or  by 
using  a  larger  cup.  We  cannot  well  breathe  faster,  unless  we 
are  exercising,  but  we  can  take  more  air  at  a  breath ;  and  this 
we  ought  to  do  as  often  as  we  can,  not  only  full  inspirations, 
but  deep  expirations  as  well.  Frequently  during  our  study 
hours  it  will  pay  us  to  stand  erect  and  take  a  number  of  full 
breaths,  with  the  window  open  (if  the  weather  will  permit), 
so  that  the  quality  9f  the  air  may  be  as  good  as  possible. 
The  position  while  sitting  ought  to  receive  careful  attention, 
for  a  cramped  position  will  reduce  the  quantity  of  air  taken 
in  at  each  breath.  It  is  a  good  general  rule  to  sit  with  the 
lower  part  of  the  back  against  the  lower  part  of  the  chair-back. 
If  one  forms  this  habit,  and  resists  the  temptation  to  slide 
down  in  the  seat,  thus  curving  the  body  and  cramping  the 
lungs,  it  will  be  of  great  benefit.  In  walking,  it  is  of  great 
value  to  the  lungs  to  have  an  erect  carriage,  as  well  as  greatly 
improving  the  personal  appearance.  To  hold  the  chest  well 
forward,  and  the  chin  well  in,  is  of  the  utmost  importance  to 
every  one,  and  should  not  be  left  to  the  military  cadets.  It 
will  aid  the  health  and  appearance  of  other  students  as  much 


HYGIENE   OF  BREATHING.  121 

as  it  does  in  the  case  of  these  young  men,  whose  health  and 
carriage  are  universally  admired. 

Those  persons  who  take  constant  exercise  in  the  open  air 
are  not  likely  to  suffer  much  from  deficient  respiration.  But 
persons  following  sedentary  occupations,  such  as  that  of  the 
student,  not  calling  for  deep  breathing  (and  often  the  air 
taken  in  is  of  poor  quality),  need  to  pay  especial  attention  to 
the  matter. 

The  fact  has  been  noted  that  breathing  directly  aids  the 
circulation  of  the  blood.  This  is  due  to  the  way  air  pressure 
is  made  to  affect  the  large  veins.  Breathing  also  may  very 
considerably  aid  the  flow  of  lymph.  Every  deep  inspiration 
brings  pressure  to  bear  on  the  main  lymph  duct  as  the  dia- 
phragm descends.  Every  forced  expiration  has  the  same 
effect.  Now,  we  must  keep  in  mind  that  the  tissues  are  fed 
directly  by  the  lymph  that  surrounds  them ;  that  while  the 
lymph  is  continually  fed  by  the  blood,  there  is  not  a  great 
pressure  given  in  this  way.  The  lymph  stream  is  largely  de- 
pendent on  the  pressure  of  the  surrounding  organs.  When 
one  takes  a  good  deal  of  muscular  exercise  the  lymph  is  re- 
newed with  rapidity  enough  to  supply  the  tissues  with  food, 
and  to  carry  away  their  wastes.  But  for  those  who  sit  quiet 
a  large  share  of  the  day,  taking  no  more  exercise  than  is  ne- 
cessary to  take  them  to  and  from  their  places  of  business,  it  is 
well  to  give  this  matter  especial  attention.  Deep  breathing, 
regularly  practiced  several  times  a  day  for  a  few  minutes  at  a 
time,  is  very  beneficial. 

It  is  a  grateful  relief  to  the  whole  system  to  stand,  stretch, 
inhale  deeply  and  slowly  several  times,  and  to  repeat  this 
every  hour  or  so.  Every  one  engaged  in  office  work  or  study- 
ing should  form  this  habit,  especially  if  he  does  not  give  an 
hour  daily  to  exercise  in  a  gymnasium,  or  otherwise. 

Respiratory   Sounds.  —  During   respiration   sounds   are 


122  CONTROL    OF  RESPIRATION. 

produced  by  which  the  skilled  physician  can  tell  much  as  to 
the  condition  of  the  respiratory  organs. 

The  Control  of  Respiration.  —  Breathing  is  an  involun- 
tary act.  Still  we  can  modify  it.  We  can  hold  the  breath 
for  a  time ;  but  it  is  stated  that  one  cannot  hold  the  breath 
long  enough  to  produce  death  by  suffocation. 

The  muscles  of  respiration  are  under  the  control  of  nerves. 
The  center  of  respiratory  control  is  believed  to  be  in  the 
lower  portion  of  the  spinal  bulb.  This  Respiratory  Center  is 
one  of  the  most  vital  points  in  the  body ;  for  if  it  is  de- 
stroyed, breathing  is  completely  stopped,  and  death  ensues. 
This  center  is  affected  by  the  condition  of  the  blood.  For 
instance,  if  the  blood  going  to  this  center  has  not  enough 
oxygen,  the  center  hastens  the  process  of  breathing  by  nerve 
impulses  sent  to  the  muscles  of  respiration. 

The  diaphragm  is  under  the  control  of  the  phrenic  nerves, 
which  arise  from  the  third,  fourth,  and  fifth  cervical  nerves. 
If  the  neck  is  broken  above  the  point  where  these  nerves  are 
given  off,  death  almost  always  immediately  follows,  because 
the  connection  of  the  respiratory  center  and  the  diaphragm  is 
broken. 

COMPOSITION   OF  THE   AIR. 

Dry  air  contains,  by  volume,  about  as  follows :  — 

Oxygen 21.00 

Nitrogen 79.00 

Carbon  Dioxid    .  .04 


100.04 

Various  gases  are  found  in  the  air  in  small  quantities. 
About  one  per  cent  of  what  is  classed  as  nitrogen  in  the  above 
table  is  now  known  to  be  a  distinct  element  called  Argon. 

If  we  would  understand  the  results  of  respiration,  how  the 
air  does  its  proper  work  in  our  bodies,  and  how  our  bodies 


CHEMISTRY  OF  RESPIRATION.  123 

produce  the  changes  in  the  air  that  passes  through  the  lungs, 
we  must  know  something  about  the  gases  that  are  the  con- 
stant components  of  that  which  we  breathe. 


EXPERIMENTS    ILLUSTRATING    THE    CHEMISTRY    OP 
RESPIRATION. 

MATERIALS.  —  Soup-plate  or  basin,  two  quart  fruit-jars, 
piece  of  phosphorus  half  the  size  of  a  pea,  chalk  crayon,  strip 
of  sheet-lead  one  inch  wide  and  eight  inches  long,  fine  wire 
one  foot  long,  pail  of  water,  cup,  matches,  watchspring,  mag- 
nesium ribbon  four  inches  long,  two  horse-radish  bottles,  four 
tumblers  (two  should  be  kept  in  a  cool  place),  lime-water  (pre- 
pared a  day  or  two  beforehand,  by  putting  a  piece  of  quick- 
lime about  the  size  of  a  hen's  egg  into  a  quart  of  water ;  pour 
off  the  clear  liquid  for  use  in  experiments),  wax  tapers,  rubber 
tubing  (two  feet),  bellows,  splints,  corks,  apparatus  for  gene- 
rating oxygen  and  carbon  dioxid  (consult  any  chemistry). 

CAUTION.  —  Always  handle  phosphorus  with  forceps,  not 
with  the  fingers.  Cut  it  under  water,  in  a  plate. 

PREPARATION.  —  Hollow  out  the  •  large  end  of  the  crayon, 
and  wire  it  to  one  end  of  the  lead  strip.  Bend  the  strip  so 
that  the  crayon  cup  will  be  held  at  half  the  height  of  the  jar, 
and  set  it  on  the  plate.  Lay  the  piece  of  phosphorus  in  the 
chalk  cup  made  of  the  crayon ;  pour  a  little  water  into  the 
plate. 

EXPERIMENT  1.  —  Ignite  the  phosphorus,  and  lower  the  in- 
verted jar  over  it.  Keep  the  mouth  of  the  jar  covered  with 
water,  adding  more  if  some  of  the  water  is  drawn  up  into  the 
jar. 

EXPLANATION.  -»—  The  phosphorus  in  burning  unites  with 
the  oxygen  of  the  air,  forming  a  white  cloud  of  phosphoric 
oxid.  This  is  gradually  absorbed  by  the  water,  and  the  pres- 


124  CHEMISTRY   OF  RESPIRATION. 

sure  of  the  outside  air  pushes  water  up  into  the  jar  to  take 
the  place  of  the  oxygen  that  has  been  removed.  The  clear 
gas  left  when  the  cloud  disappears  is  nitrogen.  What  part 
of  the  jar  is  occupied  by  the  nitrogen  ?  What  part  of  the  air 
is  oxygen  ?  Of  course  this  experiment  will  not  show  these 
proportions  very  accurately. 

EXPERIMENT  2.  —  After  the  gas  remaining  in  the  jar  has 
become  clear,  carefully  lift  the  plate  and  jar,  and  lower  them 
into  a  pail  of  water  until  the  mouth  of  the  jar  is  well  under 
the  water.  Hold  the  jar  with  one  hand,  and  let  the  plate  and 
lead  sink.  Slip  the  palm  of  the  hand  over  the  mouth  of  the 
jar,  and  invert  the  jar  and  set  it  on  the  table,  keeping  the 
hand  firmly  over  the  mouth  of  the  jar.  Slowly  lower  a  lighted 
taper  into  the  jar.  The  flame  is  extinguished.  Quickly  cover 
the  jar  and  repeat  the  experiment.  The  nitrogen  does  not 
support  combustion.  If  an  animal  were  put  into  a  jar  of 
nitrogen,  it  would  soon  die ;  not  because  the  nitrogen  injures 
it  in  any  way,  but  simply  because  nitrogen  does  not  support 
respiration. 

Nitrogen  makes  up  four-fifths  of  the  air  and  oxygen  one- 
fifth. 

EXPERIMENT  3.  —  Into  a  jar  of  oxygen  lower  a  splinter 
with  a  live  coal  at  the  end  (left  after  blowing  out  the  flame). 
The  coal  is  kindled  into  flame.  This  shows  the  chief  prop- 
erty of  oxygen ;  that  is,  its  power  of  supporting  combustion. 

EXPERIMENT  4.  —  Into  a  jar  of  carbon  dioxid  lower  a 
lighted  taper.  It  is  at  once  extinguished. 

Carbon  dioxid  may  easily  be  generated  by  such  means  as 
are  at  hand  in  every  kitchen.  Baking-powder  liberates  carbon 
dioxid  freely  when  water  is  added  to  it.  Put  some  baking- 
powder  into  a  tumbler,  and  pour  water  upon  it.  The  carbon 
dioxid  may  be  poured  into  another  tumbler  and  tested.  Better 
put  the  baking-powder  into  a  bottle,  or  Florence  flask,  fitted 


EXPERIMENTS   IN  RESPIRATION.  125 

with  a  cork  having  a  tube  (glass  and  rubber),  so  the  gas  can 
be  collected.  Or  the  baking-powder  may  be  placed  in  a  saucer, 
a  funnel  inverted  over  it,  and  a  rubber  tube  slipped  on  the  end 
of  the  funnel  for  a  delivery  tube.  Collect  two  jars'  or  tum- 
blers of  carbon  dioxid. 

EXPERIMENT  5. — Into  ajar  or  tumbler  of  carbon  dioxid 
pour  a  little  lime-water,  and  shake  it  vigorously,  holding  one 
hand  over  the  top  of  the  jar.  The  lime-water  is  turned  milky. 
This  is  the  test  of  carbon  dioxid. 

EXPERIMENT  6. — Pour  a  little  lime-water  into  a  jar,  and 
breathe  through  it  by  means  of  a  glass  tube.  The  lime-water 
is  rendered  milky,  thus  showing  the  presence  of  carbon  dioxid 
in  the  expired  breath. 

EXPERIMENT  7.  —  Invert  a  jar  over  a  burning  taper.  The 
light  is  soon  extinguished.  Pour  a  little  lime-water  into 
the  jar,  and  shake  it  actively.  Is  carbon  dioxid  produced 
by  the  burning  taper  ?  The  oxygen  of  the  air  unites  with 
the  carbon  of  the  taper  and  forms  carbon  dioxid. 

EXPERIMENT  8.  —  Over  a  burning  taper  invert  a  clean,  cold 
jar.  A  film  of  moisture  is  seen  on  the  inside  of  the  jar. 
This  water  vapor  was  produced  by  the  burning  of  the  taper. 

EXPERIMENT  9.  —  Breathe  into  a  cold  glass  jar.  The  mois- 
ture from  the  breath  is  condensed  on  the  inside  of  the  jar. 

EXPERIMENT  10.  —  Burn  a  watchspring  in  oxygen.  Iron 
oxid,  or  iron-rust,  is  the  only  product,  while  much  heat  and 
light  are  given  off. 

EXPERIMENT  11.  —  Place  a  piece  of  watchspring  in  a  glass 
of  water.  The  next  day  we  shall  find  it  has  rusted.  This 
rust  is  iron  oxid,  the  same  as  the  iron  oxid  produced  by  the 
rapid  oxidation  which  we  called  combustion. 

EXPERIMENT  12.  —  Burn  a  piece  of  magnesium  ribbon.  It 
gives  an  intense  white  light,  and  the  only  product  of  the  com- 
bustion is  a  white  ash,  magnesium  oxid. 


126  CHEMISTRY  OF  RESPIRATION. 

EXPERIMENT  13.  —  Scrape  a  piece  of  magnesium  ribbon 
bright,  and  place  it  in  a  glass  of  water.  In  a  day  or  so  it  will 
be  found  to  be  coated  with  a  white  substance,  which  is  mag- 
nesium oxid,  the  same  as  was  produced  by  the  rapid  oxida- 
tion, or  combustion.  In  the  latter  experiment  we  should 
probably  call  it  magnesium  rust. 

EXPERIMENT  14.  —  Exhale  slowly  through  a  tube  extend- 
ing to  the  bottom  of  a  fruit-jar.  Continue  exhaling  for  a  long 
time,  to  be  sure  to  drive  out  the  air  that  was  in  the  jar.  Cap 
the  jar  tightly,  and  set  it  in  a  warm  place  for  twenty-four 
hours.  It  will  have  a  bad  odor  from  the  putrefaction  of  the 
organic  matter  thrown  out  in  the  wastes  from  the  tissues. 

EXPERIMENT  15.  —  With  a  pair  of  bellows  force  the  air  of 
the  room  through  a  small  quantity  of  lime-water.  By  con- 
tinuing the  process  for  a  long  time  it  may  be  shown  that  there 
is  carbon  dioxid  in  the  air,  but  not  nearly  so  much  as  in  the 
expired  breath. 

EXPERIMENT  16.  —  Exhale  for  a  long  time  through  a  small 
quantity  of  sulphuric  acid  (chemically  pure),  using  a  pipette 
with  a  large  bulb,  so  that  the  acid  could  not  be  drawn  up  into 
the  mouth  (the  acid  is  very  strong).  The  acid  will  gradually 
grow  dark  colored,  indicating  the  presence  of  organic  matter. 

EXPERIMENT  17.  —  Hold  a  thermometer  at  arm's  length. 
It  indicates  the  temperature  of  the  air  —  of  the  air  that  you 
are  breathing  in.  Breathe  for  a  few  minutes  upon  the  bulb  of 
the  thermometer,  and  the  fact  is  clearly  shown  that  the  air 
we  breathe  out  is  much  warmer  than  the  air  that  we  breathe 
in. 

These  experiments  show  that  breathed  air  has  gained :  — 

1.  Heat. 

2.  Water  vapor. 

3.  Carbon  dioxid. 

4.  Waste  products,  or  impurities,  having  no  definite  name, 


INSPIRED  AND   EXPIRED   AIR. 


'121 


because  not  well  known,  highly  putrescible,  often  called  by 
the  general  name  of  "  organic  waste  matter." 

Let  us  compare  the  inspired  and  expired  air  in  its  compo- 
sition. 


//V.10OOO   VOLUMES. 

(Represented  by  large  square.) 

PER  CENT. 


COMMON  FRACTION. 


AMOUNT  OF  CARBON 

DIOXID 

IN 

INSPIRED  AIR.     EXPIRED  AIR. 
4  400 

(Small  square.)         (Medium  square.) 


.04 

1 
2500 


4 

1 
25 


2  2O 

Fig.  47.    Amount  of  Carbon  Dioxid  in  Inspired  and  Expired  Air. 


100 


Inspired  air  contains  in  one  hundred  parts,  as  compared 
with  expired  air :  — 

Oxygen.     Nitrogen.     Carbon  Dioxid. 
Inspired  air  .     .     .  21  79  .04 

Expired  air  .     .     .  16  79  4.00 


128  CHANGES  IN  BLOOD  IN   THE  LUNGS. 

While  the  amount  of  nitrogen  remains  about  the  same, 
some  oxygen  has  disappeared,  and  its  place  is  taken  by  carbon 
dioxid,  while  the  amount  of  carbon  dioxid  has  increased  a  hun- 
dred-fold. 

Whatever  the  air  coming  from  the  lungs  contains  that 
was  not  in  the  air  entering  them,  it  has  taken  from  the  blood, 
and  what  the  air  has  lost  it  has  given  to  the  blood.  The  air 
in  the  air  vesicle  is  separated  from  the  blood  in  the  pulmonary 
capillaries  only  by  the  thin  wall  of  the  air  vesicle  and  the  thin 
capillary  wall.  Carbon  dioxid,  water,  and  other  waste  mat- 
ters pass  from  the  blood  through  this  thin  partition  into  the 
air  vesicle,  to  be  sent  out  by  later  expiration.  Oxygen  from 
the  air  in  the  vesicle  passes  through  these  layers  into  the 
plasma,  and  most  of  it  is  quickly  picked  up  by  the  colored 
corpuscles.  The  colored  corpuscles  are  the  Carriers  of  Oxygen. 
As  has  already  been  stated,  the  hemoglobin  in  the  colored  cor- 
puscles has  an  affinity  for  oxygen.  Hemoglobin  is  of  a  dark 
color,  and  gives  the  dark  color  to  the  blood  which  enters  the 
lungs.  When  oxygen  unites  with  the  hemoglobin  it  forms 
Oxy-hemoglobin,  which  is  of  a  bright  red  color.  Hence  the 
change  in  the  color  of  the  blood  in  the  lungs  from  a  dark 
bluish-red  to  a  bright  scarlet.  This  bright  blood  is  usually 
called  "  Arterial/'  and  the  dark  "  Venous ; "  but  it  must  be 
remembered  that  the  blood  in  the  pulmonary  artery  is  dark, 
and  in  the  pulmonary  veins  bright. 

Since  the  hemoglobin  is  dark,  and  gives  the  so-called  "  ve- 
nous "  blood  its  color,  we  might  appropriately  call  the  blood 
that  enters  the  lungs  "  hemoglobin  blood."  Since  the  hemo- 
globin takes  oxygen,  becomes  bright  red,  and  gives  the  blood 
its  bright  color  as  it  leaves  the  lungs,  no  more  suitable  name 
can  be  given  to  it  than  "  oxy-hemoglobin  blood."  The  only 
good  objection  to  these  terms  is  their  length ;  but  since  they 
are  exact,  while  the  commonly  used  terms  are  inexact,  these, 


CHANGES  IN  AIR  IN   THE  LUNGS. 


129 


or  similar  ones,  should  be  adopted.  We  might  say  "  oxygen- 
ated blood,"  and  "  de-oxygenated  blood ; "  but  here,  again,  is 
a  chance  for  misunderstanding,  for  the  blood  still  has  con- 
siderable oxygen  when  it  enters  the  lungs  (unless  of  an  ani- 
mal suffocated).  We  have  just  seen  that  in  breathing  we 


BRONCHIAL  TUBE 


FROM  PULMONARY  ARTERY 


TO  PULMONARY  VEIN 


Fig.  48.    Exchanges  between  the  Air  and  the  Blood  In  the  Lungs. 

only  take  into  the  blood  about  one-fourth  of  the  oxygen  of 
the  air  that  passes  through  the  lungs.  In  like  manner  the 
blood,  passing  through  the  tissues,  gives  up  to  those  tissues 


130  GASES  IN   THE  BLOOD. 

(in  ordinary  circumstances)  only  about  half  the  oxygen  it  con- 
tains (perhaps  holding  the  remainder  as  a  reserve). 

How  can  the  amount  of  oxygen  and  other  gases  in  the 
blood  be  determined  ?  Or  how  can  we  find  how  much  air  is 
dissolved  in  water  exposed  to  air  ?  By  placing  the  liquid 
under  the  receiver  of  an  air-pump,  and  removing  the  air  above 
the  liquid.  If  a  tumbler  of  water  be  thus  placed,  on  working 
the  pump,  bubbles  of  air  will  be  seen  rising  from  the  water. 
This  may  be  measured,  and  we  can  learn  how  much  air  a  fish 
has  in  a  given  quantity  of  water. 

If  a  quart  of  blood  be  placed  under  the  receiver,  and  the 
air  exhausted,  it  will  be  found  that  the  blood  contained  about 
three-fifths  of  a  quart  of  gas. 

This  gas  is  a  mixture  of  oxygen,  carbon  dioxid,  and  nitro- 
gen ;  and  the  proportions  vary  according  to  the  kind  of  blood 
taken.  If  from  the  left  heart,  or  pulmonary  veins,  there  will 
be  more  oxygen  and  less  carbon  dioxid ;  if  from  the  right 
heart,  or  pulmonary  artery,  or  caval  veins,  there  will  be  less 
oxygen  and  more  carbon  dioxid.  Oxy-hemoglobin  blood  ("  ar- 
terial blood  ")  contains  about  one-fifth  its  volume  of  oxygen. 
Hemoglobin  blood  ("  venous  blood  ")  contains  about  one-tenth 
its  volume  of  oxygen.  Oxy-hemoglobin  holds  about  two-fifths 
its  bulk  of  carbon  dioxid,  while  hemoglobin  blood  has  nearly 
one-half  its  bulk  of  carbon  dioxid.  In  one  hundred  volumes 
of  hemoglobin  ("  venous  ")  blood,  the  oxygen  varies  from  eight 
to  twelve  volumes.  Taking  the  average  as  ten,  the  following 
table  shows  :  — 

THE   OASES  IN  THE   BLOOD. 

From  100  volumes  of  —  May  be  obtained 


Oxygen.     Carbon  dioxid.     Nitrogen. 

Oxy-hemoglobin  (arterial)  blood      20  vols.  40  vols.         1  to  2  vols. 

Hemoglobin  (venous)  blood     .     .    10    "  46    "  1  to  2    " 


CHANGES  IN   COLOR   OF  BLOOD. 


131 


The  changes  that  take  place  in  the  color  of  the  blood,  both 
in  the  lungs  and  in  the  tissues  of  the  other  parts  of  the  body, 
may  be  illustrated  as  follows :  Prepare  a  heart  as  directed  on 
page  64.  Use  for  the  liquid  a  strong  solution  of  litmus,  neu- 
tralized or  slightly  alkaline ;  place  in  the  throat  of  each  fun- 
nel a  small  sponge.  Saturate  with  ammonia  the  sponge  in  the 
funnel  representing  the  capillaries  of  the  body,  and  saturate 
the  one  in  the  funnel  representing  the  capillaries  of  the  lungs 
with  hydrochloric  acid. 


OPEN  AURICULO-VENTRICULAR  VALVES 


<*3S?S6< 

Fig.  49.     Diagram  of  the  Circulation  of  Blood.     (Dorsal  View.) 

Now,  on  working  the  heart  the  liquid  will  change  from  red 
to  blue  in  the  funnel  representing  the  body,  and  from  blue  to 
red  in  the  funnel  representing  the  lungs. 

"  Anatomically  there  are  two  lungs,  and  the  heart  lies  be- 
tween them;  physiologically,  the  lungs  form  a  single  organ, 
which  is  interposed  between  the  two  hearts."  —  WILDER. 


132  HEAT  AND  MOTION. 

AY  hat  does  the  blood  do  with  the  oxygen  that  it  gets  in  the 
lungs  ?  and  where  did  it  get  the  carbon  dioxid  and  other  im- 
purities that  it  brings  to  the  lungs  ?  Let  us  follow  the  blood 
and  see.  From  the  pulmonary  veins  the  blood  goes  to  the  left 
heart,  and  is  pumped  to  all  the  tissues  except  the  lungs.  Let 
us  follow  a  branch  of  the  aorta  that  leads  to  a  muscle. 

The  Production  of  Heat  and  Motion  in  the  Body. — 
When  a  muscle  works  it  becomes  warmer.  This  has  been 
repeatedly  proved  by  experiment.  We  know  that  we  feel 
warmer  when  we  exercise.  We  know  that  the  blood  is  flow- 
ing more  rapidly  through  the  muscle  when  it  is  at  work. 
This  more  rapid  stream  brings  the  muscle  more  oxygen. 
This  it  needs,  for  the  heat  of  the  muscle  is  produced  by  the 
oxidation  of  substance  in  the  muscle.  We  have  seen  that 
the  oxidation  of  iron  produces  heat,  and  it  is  the  oxidation 
of  the  materials  in  the  candle  that  enables  it  to  give  out  heat. 
But  our  bodies  do  not  give  out  the  intense  heat  of  a  burning 
candle,  nor  do  they  produce  light,  as  is  the  case  with  the  oxi- 
dation of  iron  and  magnesium  when  those  metals  are  burned. 
The  slow  oxidation  of  the  metals,  in  the  presence  of  moisture, 
is  more  like  the  oxidations  in  our  bodies.  It  is  by  the  (com- 
paratively slow)  ozidations  of  the  muscle  (or  substance  in  it) 
that  the  muscles  produce  heat,  and  that  form  of  energy  which 
gives  motion.  In  the  case  of  the  rusting  of  the  metals  there 
is  as  much  heat  produced  as  when  they  are  burned ;  but  the 
heat  is  so  slowly  generated  that  it  is  given  off  about  as  fast 
as  it  is  produced,  and  we  do  not  notice  it.  The  oxidation 
produces  the  waste  matters,  just  as  the  burning  of  the  various 
substances  produces  waste. 

In  our  experiments  with  oxygen  we  see  that  substances 
which  burn  in  air  will  burn  still  more  actively  in  oxygen. 
But  we  must  not  infer  from  this  that  in  our  bodies  the  oxida- 
tion of  the  tissues  would  be  faster  in  pure  oxygen.  This  is 


WORK  AND  EESPIEATION.  133 

not  the  case.  The  tissues  take  as  much  oxygen  as  they  need 
(if  they  can  get  it)  5  and  they  will  not  take  any  more  than  they 
need,  no  matter  how  much  is  offered  them.  It  does  not  injure 
the  body,  nor  any  part  of  it,  to  breathe  pure  oxygen.  It  does 
not  make  one  feverish,  it  does  not  produce  any  more  heat,  nor 
make  one  "live  faster."  This  point  should  be  specially  no- 
ticed, as  it  was  formerly  supposed  that  the  oxidation  of  the 
tissues  of  the  body  was  just  like  any  combustion  of  dead 
material.  But  the  tissues  are  alive.  They  know  their  own 
needs.  Each  cell  takes  what  it  requires  and  no  more,  just  as 
it  does  of  food  brought  to  it  by  the  blood.  The  amount  of 
oxygen  present  does  not  determine  the  degree  of  muscular 
activity,  but  the  degree  of  muscular  activity  determines  the 
amount  of  oxygen  consumed. 

When  we  exercise,  the  muscles  need  more  oxygen.  They 
also  need  to  have  removed  the  waste  matters  that  they  are  so 
rapidly  producing  at  this  time.  How  is  the  oxygen  brought 
and  the  waste  removed  ?  By  the  blood,  you  answer.  True ; 
but  what  makes  the  blood  come  and  go  faster  at  this  time  ? 
By  reflex  action,  you  reply.  The  muscles  send  a  message  to 
a  nerve  center ;  and  this  nerve  center  sends  back  a  message 
to  the  blood  tubes,  making  them  widen,  and  the  heart  also 
may  be  made  to  beat  faster.  But  would  it  do  any  good  to 
have  the  blood  flow  through  the  muscles  faster,  if  it  could 
not  bring  more  oxygen,  and  take  away  and  get  rid  of  more 
wastes  ?  You  will  say  no.  To  give  the  extra  oxygen,  and 
take  out  the  carbon  dioxid,  the  lungs  cannot,  of  themselves, 
take  in  and  send  out  air.  The  work  of  pumping  air  depends 
on  the  muscles  of  respiration,  the  diaphragm,  and  the  muscles 
that  elevate  the  ribs.  These  will  not  work  faster  unless  they 
are  ordered  to  do  so.  A  message  must  be  sent  to  these  tell- 
ing of  the  need  in  the  muscles  that  we  are  considering,  say 
one  of  the  large  muscles  of  the  lower  limbs.  Thus,  by  a 


134  OXIDATION   OF  TISSUE. 

series  of  reflex  actions,  all  these  processes  are  kept  in  harmo- 
nious relation  to  each  other.  It  must  be  borne  in  mind  that 
increased  blood-flow  is  the  consequence,  and  not  the  cause,  of 
the  increased  activity  of  the  tissues. 

The  tissues  'of  the  body  are  oxidizing  all  the  time.  But 
when  they  are  in  vigorous  action  they  oxidize  very  much 
more  rapidly. 

Insert  the  bulb  of  a  thermometer  into  the  mouth,  and  keep 
it  there  three  or  four  minutes  to  find  the  temperature  of  the 
inside  of  the  body.  For  this  it  is  better  to  use  a  clinical 
thermometer,  if  one  can  be  obtained.  The  average  tempera- 
ture of  the  tissues  within  the  body  is  about  98.5°  F. 

The  body  may  be  compared  to  a  stove.  Into  one  we  put 
fuel  and  produce  heat.  In  the  other  we  get  heat  from  food. 
But  the  body  is  not  like  the  stove  in  burning  the  fuel  (food) 
directly.  The  food  is  first  made  into  tissues,  or  "  storage 
compounds  "  in  the  tissues.  It  is  as  though  we  were  to  build 
a  stove  entirely  of  coal,  and  then  start  a  fire  in  it.  In  that 
case  it  would  produce  heat  not  merely  by  burning  in  one 
place  within,  but  would  be  burning  throughout  the  whole  of 
its  substance.  This  is  the  case  with  the  body. 

We  have  seen  that  the  muscles  constitute  nearly  half  of 
the  weight  of  the  body.  We  know,  too,  that  muscular  tissue 
is  more  active  than  most  of  the  tissues.  We  would  now 
naturally  infer,  as  indeed  is  the  fact,  that  it  is  the  chief  source 
of  the  heat  produced  in  our  bodies. 

Next  to  the  muscles,  in  importance  as  a  heat  producer,  is 
the  liver,  which  is  the  largest  gland  in  the  body,  and,  as  we 
shall  soon  see,  one  of  the  most  active.  The  blood,  as  it  leaves 
the  liver  by  the  Hepatic  veins,  is  hotter  than  anywhere  else  in 
the  body. 

But  it  will  be  better  to  compare  the  body  to  a  locomotive, 
as  we  produce  not  only  heat,  but  motion  as  well. 


MAN  AND  LOCOMOTIVE.  135 

If  a  visitor  from  another  planet,  unfamiliar  with  such 
creatures  as  we  are,  were  to  observe  closely  a  man  and  a  loco- 
motive, he  would  see  several  points  in  common :  — 

1.  Both  are  warm. 

2.  Both  move. 

3.  Both  use  fuel  (food  and  coal). 

4.  Both  take  in  air,  and  (if  it  were  a  winter  day) 

5.  Both  give  off  smoke  (which  is  essentially  the  same  in 
the  two,  carbon  dioxid  and  water  vapor  being  the  chief  con- 
stituents). 

By  a  closer  examination  he  would  find  out  some  of  the 
differences  that  we  have  noticed  :  — 

1.  That  the  body  does  not  get  hot  enough  to  burn;  i.e.,  the 
oxidation  is  relatively  slow,  and  is  not  combustion. 

2.  That  the  oxidation  of  the  body  never  produces  light. 

3.  That  the  oxidation  here  is  always  in  the  presence  of 
moisture. 

When  the  breath  is  held  for  some  time,  the  carbon  dioxid 
in  the  expired  air  may  reach  7  or  8  per  cent. 

During  violent  exercise  the  amount  of  carbon  dioxid  given 
off  may  be  from  two  to  two  and  a  half  times  as  much  as  when 
we  are  at  rest. 

The  amount  of  carbon  dioxid  given  off  is  increased  in  cold 
weather,  and  by  taking  food ;  is  from  one-fifth  to  one-fourth 
less  during  sleep. 

Oxygen  is  carried  chiefly  in  the  corpuscles,  but  the  carbon 
dioxid  is  carried  in  both  plasma  and  corpuscles. 

The  activity  of  the  tissues  from  their  oxidation  does  not' 
necessarily  mean  that  the  oxidation  is  direct;  that  is,  that 
the  oxygen  is  used  as  soon  as  it  is  brought  to  the  tissue.  For 
instance,  in  the  muscles  it  is  believed  that  the  oxygen  is  stored 
in  some  form,  probably  in  combination,  so  that  it  can  be  used 
when  needed,  perhaps  much  more  rapidly  than  could  be  sup- 


136  SUMMARY  OF  RESPIRATION. 

plied  by  the  respiration  at  the  time.  If  we  study  the  chemis- 
try of  explosion,  we  learn  that  it  is  a  very  rapid  combustion. 
In  the  explosives  are  materials  that  unite  instantaneously, 
instead  of  slowly  burning,  as  in  the  case  of  ordinary  com- 
bustibles. 

Now,  many  physiologists  hold  that  a  sort  of  explosive  com- 
pound is  formed  in  the  muscles,  and  that  when  the  muscle 
acts  it  does  so  as  the  result  of  the  explosion,  so  to  speak,  of 
this  material.  And,  to  carry  out  the  figure,  the  nerve  is  com- 
pared to  the  match  that  ignites  the  explosive.  A  little  heat 
is  enough  to  cause  the  most  violent  explosion.  So  the  force 
that  passes  along  a  nerve  fiber  is  slight.  But  it  rouses  a  great 
amount  of  energy  that  lay  dormant  in  the  muscle.  It  would 
seem  to  have  "  touched  off  "  a  lot  of  explosive  material  that 
was  already  there,  rather  than  merely  started  an  action  that 
depends  on  the  comparatively  slow  process  of  respiration  at 
the  time.  We  cannot  follow  this  theory  farther,  as  it  takes 
us  too  deep  into  the  study  of  chemistry  in  its  most  difficult 
branch,  —  physiological  chemistry. 

We  may  thus  sum  up  respiration  :  — 

The  tissues  need  oxygen  ;  air  is  pumped  into  the  lungs ; 
this  air  gives  oxygen  to  the  blood ;  the  blood  carries  it  to  the 
tissues. 

In  oxidizing,  the  tissues  produce  energy  (heat  and  motion), 
and  give  off  waste  matter  (water,  carbon  dioxid,  etc.)  ;  these 
the  blood  carries  to  the  lungs,  the  lungs  give  them  to  the  air, 
and  the  air  carries  them  out  of  the  body. 

The  pumping  of  the  air  in  and  out  may  be  called  mechanical 
respiration.  The  changes  between  the  air  and  the  blood  in 
the  lungs  we  will  call  the  ventilation  of  the  blood,  and  the  in- 
teraction of  the  blood  and  the  tissues  the  real,  or  internal 
respiration.  (Compare  Figs.  38,  48,  and  49.) 

The    Two    Breaths.  — "  Every   time    you    breathe    you 


IMPURITIES  IN  AIR.  137 

breathe  two  different  breaths ;  you  take  in  one,  you  give  out 
another.  The  composition  of  these  two  breaths  is  different. 
Their  effects  are  different.  The  breath  which  has  been 
breathed  out  must  not  be  breathed  in  again." KINGSLEY. 

The  air  in  the  vesicles  receives  from  the  blood  carbon 
dioxid,  water  vapor,  and  other  impurities  above  mentioned. 
It  has  been  believed  for  a  number  of  years  that  the  organic 
impurities  constitute  the  most  dangerous  element  in  expired 
air.  Carbon  dioxid,  though  to  some  extent  a  poison,  is  not 
very  injurious  in  sucli  quantities  as  ordinarily  exist  in  the 
air,  even  in  poorly  ventilated  rooms ;  while  the  headache  and 
drowsiness  that  one  experiences  in  a  close  room  where  there 
are  a  number  of  people  is  due  to  the  reabsorption  of  these 
organic  matters.  It  is  not  due  to  lack  of  oxygen,  for  the  oxy- 
gen may  be  reduced  to  13  per  cent  without  causing  discom- 
fort. A  person  may  breathe  air  containing  one  per  cent  of 
carbon  dioxid,  with  a  corresponding  reduction  of  oxygen,  when 
the  carbon  dioxid  is  generated  by  ordinary  chemical  processes 
(as  in  a  small  room  with  a  large  kerosene  lamp,  or  a  gasoline 
stove)  ;  but  air  having  one  per  cent  of  carbon  dioxid  produced 
by  breathing  is  highly  injurious,  because  it  contains  the  or- 
ganic impurities  above  noted,  and  the  term  "crowd-poison" 
has  been  employed  for  this  material.  Later  investigators, 
however,  maintain  that  there  is  nothing  poisonous  in  the 
freshly  expired  breath. 

HEATING    AND    VENTILATION. 

We  often  hear  the  expression  "  Free  as  Air."  While  air 
is  free,  and  there  is  an  abundance  of  it,  still  the  expression  is 
practically  untrue.  In  the  temperate  and  colder  parts  of  the 
world,  and  for  many  indoor  workers,  especially  those  follow- 


138  HEATING  AND    VENTILATION. 

ing  a  sedentary  pursuit,  it  is  necessary  to  heat  the  air  for  a 
considerable  part  of  the  year.  When  one  is  actively  exercis- 
ing his  muscles  he  may  keep  warm  outdoors  through  our 
winter  days.  But,  as  we  see,  the  heat  of  the  body  depends 
on  its  internal  fires,  the  oxidation  of  its  tissues.  If  we  are 
inactive,  these  fires  burn  feebly,  and  we  need  outside  heat. 
While  air  is  free,  it  really  costs  a  good  deal  of  money  to  have 
it  properly  warmed.  We  must  have  a  constant  renewal  of 
air  or  we  suffer  greatly.  One  serious  trouble  is  that  many 
cannot  afford  (or  think  they  cannot)  to  heat  the  air  properly, 
and  many  others  are  ignorant  concerning  these  matters. 

Lung  diseases  are  rare  in  the  regions  where  the  windows 
and  doors  may  be  kept  open  most  of  the  days  of  the  year.  It 
is  from  shutting  ourselves  in  so  closely  that  we  suffer.  This 
is  especially  true  where  many  people  are  housed  in  a  compar- 
atively small  space,  as  in  many  public  buildings.  But  in  our 
private  dwellings,  even  when  the  owners  are  amply  able  to 
secure  the  most  sanatory  appliances,  defective  apparatus  is 
often  put  in.  Any  system  that  does  not  provide  for  a  constant 
renewal  of  the  air  is  defective. 

Grates  will  aid  largely  in  renewing  the  air.  Although  in 
themselves  they  merely  have  provision  for  sending  radiant 
heat  out  into  the  room  and  much  air  up  the  chimney,  yet, 
without  any  special  provision  for  inlet  of  air  to  the  room, 
they  draw  air  in  through  every  crack  and  crevice.  It  would 
probably  be  very  much  better  to  have  special  ducts  for  the 
admission  of  air  which  is  suitably  warmed  while  on  its  way 
into  the  room,  and  to  make  the  doors  shut  snugly,  and  to  have 
double  windows,  as  then  both  the  admission  of  fresh  air  and 
the  regulation  of  heat  will  be  better  secured.  But  it  is  a 
serious  question  whether,  with  all  our  modern  appliances  and 
conveniences  and  luxuries,  uniform  heat,  electric  and  other 
regulators  —  whether,  on  the  whole,  we  have  better  air  in 


PRINCIPLES   OF  VENTILATION.  139 

our  houses,  and  take  cold  less  frequently,  than  in  the  days 
when  we  depended  more  on  the  fireplace,  even  if  we  did 
"•roast  on  one  side  while  we  froze  on  the  other."  Fireplaces 
are  expensive  as  mere  heaters,  but  they  are  excellent  ventila- 
tors. If  small  ventilating  flues  could  be  built  around  the  flue 
of  the  main  heating  apparatus,  and  connected  with  the  various 
rooms  of  the  house,  air  could  be  drawn  from  these  rooms  by 
ascending  currents  created  by  the  heat  of  the  central  smoke 
flue.  Such  flues  surrounding  smoke  flues  would  have  the 
added  advantage  of  protecting  the  house  from  fire  through 
the  too  common  "defective  flue." 

The  General  Principles  of  Ventilation. — 1.  Diffusion. 
Gases  tend  to  mix.  We  know  that  if  a  bottle  containing  an 
odorous  substance  be  opened  in  a  room  where  there  are  no  air 
currents  the  odor  tends  to  spread  equally  through  the  room. 
So  if  a  person  is  in  one  corner  of  a  large  room,  where  there 
are  no  inlets  or  outlets,  and  no  currents,  as  he  uses  the  oxygen 
immediately  around  him  the  oxygen  farther  away  will  diffuse 
toward  him,  so  that  he  will  continue  to  get  oxygen  till  the 
amount  of  oxygen  in  the  room  is  nearly  exhausted.  So,  too, 
the  gases  that  he  breathes  out  will  not  remain  confined  to 
the  space  directly  about  him,  but  will  spread  nearly  evenly 
throughout  the  room.  The  same  takes  place  in  the  open  air, 
without  wind.  So,  then,  if  the  windows  and  doors  are  open, 
the  air  of  the  room  will,  by  diffusion,  be  renewed. 

2.  Wind.     Motion  of  the  air  renews  faster  than  mere  dif- 
fusion.    Strong  wind  forces  its  way  through  the  cracks  around 
windows,  and  when  windows  are  open  on  opposite  sides  of  a 
room  there  is  usually  enough  breeze  to  renew  the  air.     But 
during  the  greater  part  of  the  year  this  cannot  be  done. 

3.  Artificial  renewal  of  the  air.     The  renewal  of  the  air  in 
most  cases  depends  on  the  fact  that  heated  air  rises.     Heat 
expands  air.     It  is  then  lighter,  bulk  for  bulk,  than  cooler 


140  UEATING  AND    VENTILATION. 

air.  The  heavier  surrounding  air  presses  the  lighter  air  up- 
ward.  If  there  are  outlets  above  and  below,  the  heavier, 
colder  air  will  press  in  at  any  opening  left  below,  and  push 
the  lighter,  warmer  air  out  above.  Thus,  in  the  case  of  the 
common  stove  we  very  well  know  that  there  are  currents  of 
heated  air  rising  above  the  stove.  Children  make  whirligigs 
and  various  toys  to  place  in  these  up-currents  above  stoves. 
Air  is,  at  the  same  time,  flowing  toward  the  stove  along  the 
floor  and  lower  part  of  the  room.  Cold  air  can  usually  be 
detected  entering  around  the  windows  and  doors,  which  presses 
downward  and  toward  the  source  of  heat.  The  stove  does  not 
do  much  to  renew  the  air  in  the  room  except  in  this  general 
way;  some  heated  air  escapes  at  openings  in  the  upper  part 
of  the  room,  and  some  is  passed  out  through  the  stove,  taken 
in  as  a  draft.  But  in  the  main,  the  action  of  the  heat  of  the 
stove  is  to  make  a  current  of  warm  air  up  from  the  stove, 
which  current  passes  along  the  ceiling  to  the  more  distant 
corners  of  the  room,  then  descends,  joining  the  cold  air,  and 
repeating  the  round. 

In  some  cases  a  jacket  is  placed  around  a  stove,  and  a  duct 
from  the  outer  air  connects  with  the  lower  part  of  the  space 
inside  of  the  jacket  and  outside  of  the  stove.  Then  as  the  air 
heated  by  the  stove  rises,  fresh  air  is  drawn  in  from  outside 
to  be  warmed.  In  this  case  the  direct  heat  from  the  stove 
is  shut  off  from  the  room.  Heat  radiates  in  straight  lines. 
When  one  holds  out  his  hands  beside  a  stove  the  heat  he 
receives  is  radiant  heat.  Most  of  the  heat  from  a  grate  is 
radiant  heat.  But  in  a  jacketed  stove  the  heating  by  air 
currents  is 'called  heating  by  convection.  Now  a  furnace  is 
practically  a  jacketed  stove  (almost  always  placed  in  a  base- 
ment). Furnaces  have  this  good  feature  that  they  are  all  the 
time  sending  fresh  air  into  a  room. 

Although  in  private  dwellings  heated  by  furnaces  there  is 


HEATING  AND    VENTILATION.  141 

no  special  provision  for  the  escape  of  foul  air,  there  is  ordi- 
narily sufficient  renewal  of  the  air.  But  in  public  buildings 
there  should  be  escape  flues  for  foul  air. 

Frequently  in  later  years  a  large  foul-air  shaft  is  built  in 
some  central  part  of  the  building,  and  a  small  stove  placed  in 
it  to  create  a  sufficient  up-current. 

In  many  public  buildings  the  currents  created -by  heat  are 
insufficient  to  renew  the  air  properly.  Fans  are  used,  which 
force  the  air,  properly  heated,  into  the  room. 

In  heating  by  steam  or  hot  water,  if  the  radiators  are 
placed  in  the  room  they  give  direct,  or  radiant  heat.  This 
system  is  called  "  Direct  Heating."  In  itself  it  has  no  provis- 
ion for  renewing  the  air.  It  gives  direct  heat,  and  produces 
air  currents  within  the  room ;  and  any  change  in  the  air  is 
wholly  incidental,  from  escape  of  heated  air  in  the  upper 
parts  of  the  room  and  corresponding  suction  of  outside  air 
through  such  openings  as  the  carpenters  have  left  below. 

In  "  Indirect "  heating,  coils  of  steam  or  hot-water  pipes 
are  placed  in  air  shafts  which  lead  up  to  the  rooms  above,  and 
also  have  ducts  to  the  outside.  As  the  air  is  heated  by  the 
heat  of  the  pipes,  it  is  forced  into  the  rooms  above,  by  fresh, 
cold  air  pressing  in  through  the  ducts,  to  be,  in  turn,  heated 
and  sent  up.  If  there  is  at  the  same  time  a  proper  escape  for 
the  foul  air,  this  makes  an  excellent  system.  In  many  situa- 
tions the  direct  and  indirect  may  be  advantageously  combined. 
Where  there  is  a  grate  in  a  room  it  serves  very  well  as  a  foul- 
air  shaft,  especially  when  there  is  a  fire  in  the  grate.  It  is 
well  to  have  the  flue  from  the  grate  in  the  same  chimney  with 
that  from  the  smoke-pipe,  as  then  the  heat  from  the  smoke 
will  cause  a  constant  up-draft  in  the  grate  flue,  whether  there 
is  a  fire  going  in  the  grate  or  not. 

With  a  grate,  in  private  houses,  there  is  ordinarily  no  need 
of  other  foul-air  shaft  for  any  room.  But  it  is  very  desirable 


142       BREATHING  THROUGH  THE  MOUTH. 

to  have  at  least  some  indirect  heat,  so  that  the  fresh  air  in- 
troduced will  be  sufficiently  heated. 

If  the  introduction  of  air  is  thus  provided  for,  it  is  then 
safe  to  put  on  double  windows  and  make  the  cracks  around 
the  door  very  tight.  Without  any  special  provision  for  the 
renewal  of  the  air,  these  cracks  are  the  means  of  safety. 

In  houses  heated  by  furnaces,  steam,  or  hot  water,  the  floor 
is  likely  to  be  warmer  from  the  escape  of  heat  from  the  heater 
itself,  and  from  pipes  or  air  ducts  under  the  floor. 

There  is  a  very  common  misunderstanding  as  to  the  cold 
felt  near  a  window  in  cold  weather.  It  seems  that  air  is  enter- 
ing ;  but  a  little  reflection  will  show  that  even  if  the  window 
were  air-tight  this  effect  would  be  produced,  for  the  air  near 
the  window  is  cooled  by  losing  heat  to  the  outer  air.  The  air 
next  to  the  window,  thus  cooled,  is  heavier,  and  falls  to  the 
floor ;  and  if  there  is  any  source  of  heat  in  the  room,  this  cold 
air  will  pass  along  the  floor  to  that  source  of  heat,  up  from 
the  heating  body  to  the  ceiling,  and  across  the  ceiling,  and  so 
on  around  again.  There  may  thus  be  currents  without  any 
appreciable  change  in  the  quality  of  the  air.  It  is  economy 
to  use  double  windows,  and  prevent  the  loss  of  heat  through 
the  glass.  So  both  economy  and  comfort  suggest  to  us  that 
we  reduce  as  much  as  possible  cracks  around  doors  and  win- 
dows, use  double  windows,  make  vestibules  at  entrances,  and 
build  special  ducts  by  which  fresh  air  may  enter,  and  heat  it 
properly  on  its  way  in. 

Breathing  through  the  Mouth.  —  We  should  breathe 
through  the  nose,  and  not  through  the  mouth.  The  nasal 
passages  are  fitted  for  the  introduction  of  the  air  (1)  by  being 
narrow,  but  with  an  extended  area ;  (2)  the  lining  membrane 
is  richly  supplied  with  blood  and  (3)  secretes  an  abundant  sup- 
ply of  mucus.  The  air,  coming  through  this  narrow  channel,  is 
warmed,  and  a  large  part  of  any  dust  it  may  contain  is  caught 


DEAD  DUST.  143 

by  the  sticky  mucus  that  covers  all  the  walls  of  this  passage- 
way. If  we  breathe  through  the  mouth  (especially  out-of- 
doors  in  cold  weather),  the  air  may  not  be  sufficiently  warmed 
before  entering  the  lungs,  and  much  more  dust  would  be  car- 
ried into  the  lungs.  Then,  too,  the  air  has  a  drying  effect  on 
the  throat,  whereas  the  mucus  of  the  nasal  passages  will 
moisten  the  air  as  it  enters.  The  cilia,  which  extend  from 
most  of  the  cells  lining  the  respiratory  passages,  are  con- 
stantly causing  the  mucus  to  slowly  flow  toward  the  external 
opening,  so  a  good  share  of  the  dust  is  gotten  rid  of.  A 
further  advantage  of  breathing  through  the  nose  is  that  we 
detect  odors,  and  can  thus  judge  of  the  quality  of  the  air. 

DEAD   DUST. 

Every  one  will  recall  how  delightfully  refreshing  the  air  is 
after  a  rain  or  a  snowstorm.  This  is  not  due  merely  to  the 
fact  that  the  air  is  cool.  It  is  clean  because  it  has  been 
washed.  The  rain  and  snow  absorb  a  considerable  amount  of 
the  various  impure  gases  that  are  in  the  air.  But  raindrops 
and  sriowflakes  bring  down  with  them  many  particles  of  dust 
that  were  floating  in  the  air.  Take  some  of  the  snow  that  has 
fallen  in  a  town.  It  looks  pure  in  its  almost  dazzling  white- 
ness. But  melt  some  of  it,  and  you  will  usually  find  a  de- 
cided tinge  darkening  the  water,  showing  that  as  the  flakes 
sifted  down  through  the  air  they  caught  myriads  of  particles 
of  dust.  Where  soft  coal  is  used  to  any  large  extent  it  is  one 
abundant  source  of  this  dust.  In  summer  dust  has  many 
sources.  The  dust  that  blows  into  your  face,  and  perhaps 
into  your  mouth,  may  be  made  of  dry  soil.  Take  a  dry  clod 
and  drop  it ;  it  falls  quickly  to  the  ground.  Pulverize  it  in 
your  hand  before  dropping  it,  and  considerable  of  it  floats  in 
the  air  for  some  time.  Any  substance  that  is  easily  dried 


144  LIVE  DUST. 

and  pulverized  may  form  part  of  the  common  dust.  The  dust 
that  you  wipe  from  your  eye,  or  is  caught  by  the  mucus  of 
the  nasal  passages,  may,  instead  of  being  made  of  clean  soil, 
be  from  the  excreta  of  horses,  decayed  leaves,  wood,  grass,  etc. 
Indoors  we  are  constantly  making  dust  by  wearing  out  our 
clothes.  Many  of  the  tiny  particles  that  we  see  floating  in 
the  sunbeams  are  bits  of  cotton  or  woolen  fibers.  Shake  any 
garment  in  a  beam  of  light  to  see  how  much  dust  is  given  off, 
and  how  easily.  The  worn-off  particles  of  our  shoes,  books, 
floors,  all  contribute  to  the  ever-present  dust. 

Now,  this  dust  (so  far  as  it  is  mere  dead,  dry  matter,  not 
considering  it  as  a  poison)  is  irritating  to  the  lungs  and  res-> 
piratory  passages.  There  is  provision,  as  we  have  seen,  for 
catching  and  getting  rid  of  a  good  deal  of  it. 

But  still  much  is  taken  into  the  lungs.  Examination  shows 
that  the  lungs  have  many  black  specks  from  particles  of  car- 
bon, etc.,  that  have  become  lodged,  and  are  of  no  benefit,  to 
say  the  least. 

LIVE    DUST. 

Bad  as  this  dead  dust  is,  the  injury  from  it  is  slight  com- 
pared to  that  from  live  dust.  We  know  that  certain  seeds 
float  in  the  air,  carried  along  by  the  wind.  But  these  are 
comparatively  heavy,  and  soon  sink  to  the  ground. 

We  all  know  pollen.  At  certain  seasons  it  forms,  in  the 
vicinity  of  cornfields  for  instance,  a  considerable  part  of  the 
dust.  This  is  alive.  It  will  grow  if  it  falls  on  the  right  kind 
of  a  surface,  the  stigma  of  the  right  plant  at  the  right  time. 
Such  dust  will  not  grow  in  our  bodies.  We  do  not  furnish  a 
soil  in  which  it  can  grow.  It  merely  adds  to  the  amount  of 
irritating  dust. 

We  have  seen  puff-balls  give  off  a  cloud  of  dust  when  they 
are  crushed.  Here,  again,  this  dust  is  composed  of  live  Spores, 


DISEASE   GERMS.  145 

as  we  call  them,  that  will  grow  in  suitable  places  and  condi- 
tions. So,  too,  from  a  patch  of  mold,  when  brushed,  we 
often  see  a  little  cloud  of  dust.  These  are  a  few  instances 
of  kinds  of  living  dust  that  simply  act  on  us  like  so  much 
dead  matter. 

If  we  set  a  tumbler  of  cider  on  a  table  in  a  warm  room,  in 
a  few  days  it  ferments.  This  is  due  to  yeast  that  has  gotten 
into  it.  Boil  the  cider  to  kill  any  yeast  that  is  already  in  it, 
and  cork  it  securely  so  that  air  cannot  get  at  it,  and  it  will 
not  ferment.  Dried  yeast  germs  float  in  the  air,  settle  into 
this  exposed  cider,  and  cause  it  to  ferment.  Cider  is  a  good 
soil  for  yeast.  But  there  are  floating  in  the  air  many  kinds  of 
spores  that  may  grow  in  our  bodies.  We  know  that  many  of 
our  contagious  diseases  are  due  to  the  growth  in  our  bodies 
of  some,  of  these  spores.  Our  bodies  are  a  good  soil  for  cer- 
tain germs.  The  germs  that  cause  consumption,  typhoid-fever, 
Asiatic  cholera,  erysipelas,  diphtheria,  and  some  forms  of  blood- 
poisoning,  are  well  known.  Microscopists  know  them  when 
they  see  them  as  readily  as  we  know  peas  from  beans.  And 
it  is  proved  beyond  all  doubt  that  these  germs  get  into  our 
bodies  by  being  breathed  in,  or  by  being  eaten  in  food,  or  in 
drinking  water,  or  by  introduction  into  the  blood  in  wounds. 
We  have  reason  to  believe  that  small-pox,  yellow-fever,  mea- 
sles, and  scarlatina  are  caused  by  germs;  but  these  diseases 
have  not  been  studied  so  successfully. 

How  can  we  avoid  or  get  rid  of  dusts  of  these  kinds  ? 

To  exterminate  any  plant,  we  try  to  keep  the  seeds  from 
ripening,  and  to  kill  all  that  do  ripen.  Let  us  take  a  case 
that,  while  not  pleasant  to  contemplate,  is  too  terribly  true  to 
allow  of  being  called  an  imagined  case. 

A  consumptive  expectorates  on  the  pavement.  In  this 
sputum  are  probably  hundreds,  if  not  thousands,  of  germs 
known  as  bacilli  (Bacillus  tuberculosis).  They  are  alive. 


146  BACTERIA. 

Now,  so  long  as  they  remain  on  the  pavement  they  do  no 
harm.  The  sputum  dries.  But  the  bacilli  are  not  killed  by 
drying.  With  other  dry  material  from  the  pavement  they 
form  part  of  the  common  dust.  Any  one  of  us  may  breathe 
some  of  this  kind  of  matter  any  day,  for  there  are  persons 
afflicted  with  this  dreaded  disease  in  every  community.  Our 
bodies  furnish  the  very  best  soil  for  them  to  grow  in.  We  do 
not  need  to  go  into  the  street  to  be  exposed.  WTho  knows 
what  he  brings  into  the  house  adhering  to  his  clothing  ?  These 
germs  may  be  brought  into  the  most  cleanly  houses  in  these 
ways,  or  by  the  wind. 

Now,  of  course,  all  such  material  known  to  be  highly  dan- 
gerous ought  to  be  destroyed.  If  those  suffering  from  such 
diseases  were  careful  to  burn  all  such  matter,  most  of  the 
seeds  of  this  disease  would  be  killed.  Thus  in  time  we 
might  stamp  out  the  disease,  as  a  scourge  of  Canada  this- 
tles. But  so  long  as  people  expectorate  upon  the  floors  and 
pavements,  it  will  be  difficult  to  prevent  the  spread  of  such 
germ  diseases. 

In  hospitals  such  matters  are  now  looked  after  with  the 
greatest  care,  and  in  private  houses  where  there  is  intelligence 
on  these  subjects.  And  it  is  encouraging  to  note  the  awaken- 
ing of  the  public  to  the  significance  of  the  teachings  of  mod- 
ern science  on  this  subject,  as  shown  by  the  fact  that  many 
of  the  railroad  and  street-car  companies  now  prohibit  spitting 
on  the  floors  of  cars,  not  merely  because  it  is  uncleanly,  but  on 
the  express  ground  that  it  is  a  means  of  spreading  infectious 
diseases. 

These  disease  germs  are  the  smallest  and  simplest  of  liv- 
ing things.  They  are  plants ;  and  while  all  of  them  that  are 
well  known  have  their  scientific  names,  just  as  the  larger 
plants  have,  they  are  all  included  in  one  general  group  desig- 
nated as  Bacteria. 


Bacillus  of  Diphtheria  (x  1000). 


Bacillus  of  Tuberculosis  (x  1000). 


acillus  of  Typhoid  Fever  (x  1200). 


Bacillus  of  Typhoid   Fever  (x  1200), 
showing  flagella. 


Bacillus    (Spirillum)  of  Asiatic  Cholera. 


Bacillus  of  Hog  Cholera   (x  1000). 


TYPES  OF  BACILLI, 
Showing  Morphologic  Characters  and  Arrangement. 


To  face  page  14  7. 


HOUSE  DUST.  147 

We  need  to  learn  a  good  deal  more  about  avoiding  and 
destroying  dust,  and  the  things  that  make  dust. 

Towns  and  cities  need  more  sprinkling  to  keep  the  dust 
down.  Much  more  of  the  refuse  and  street  sweepings  and 
cleanings  ought  to  be  burned.  The  dust  of  a  house  should 
always  be  burned,  as  we  know  not  what  germs  of  disease  may 
be  in  it.  If  we  burn  it,  we  shall  surely  not  have  to  sweep  up 
that  dust  again.  If  we  send  it  out-of-doors  it  may  come  back, 
and  we  may  have  to  handle  it  again  and  again. 

So  far  as  possible  let  us  avoid  things  that  make  dust. 
When  we  sweep  a  carpet,  a  considerable  share  of  the  dust 
comes  from  the  carpet  itself,  especially  if  the  carpet  is  old. 
Curtains  and  tapestries  of  nearly  all  sorts  not  only  hold  dust, 
but  contribute  a  good  deal  to  it.  Those  who  write  on  such 
subjects  recommend  hard-wood  floors  with  rugs  instead  of 
carpets.  The  rugs  can  be  taken  out-of-doors  and  shaken,  and 
the  floors  wiped  with  a  moist  cloth,  so  that  little  dust  is  left 
floating  in  the  air  of  the  room.  Compare  this  with  the  condi- 
tion that  holds  after  the  ordinary  sweeping  of  a  carpeted  room 
with  the  common  broom.  The  dust  fills  the  air,  only  to  settle 
back  on  the  floor  and  furniture.  Then  comes  the  whisk  broom, 
the  so-called  dusting.  Well,  it  is  dusting  !  It  fills  the  air  once 
more  with  dust.  But  do  we  get  rid  of  it?  Wiping  off  the 
dust  with  a  moist  cloth  takes  most  of  it  away  on  the  cloth. 
For  those  who  cannot  have  hard-wood  floors,  a  most  excellent 
substitute  (and  in  some  respects  better)  is  oilcloth  or  linoleum. 
With  rugs  over  these,  a  house  may  be  kept  clean.  Not  wait- 
ing for  housecleaning  time  (that  reign  of  terror),  rugs  can  be 
taken  out,  and  the  floors  gone  over  with  a  moist  cloth. 

The  improved  carpet-sweepers  are  not  only  convenient,  but 
sanatory. 

Many  a  well-meaning  person  will  sweep  a  carpet  in  a  sick- 
room with  an  ordinary  broom,  when  the  patient  is  suffering 


148  DEATH  FROM   LUXG   DISEASE. 

from  lung  disease,  thoughtless  of  the  fact  that  a  little  dust  in 
sight,  and  perhaps  on  the  shoes,  is  of  much  less  significance 
than  dust  in  the  air  we  breathe.  No  one  likes  dust  on  the 
floor,  but  better  a  thousand  times  there  than  in  our  lungs. 

Statistics  seem  to  show  that  one-seventh  of  the  deaths 
among  the  civilized  races  are  due  to  lung  diseases.  The  best 
authorities  are  now  agreed  that  consumption  is  not  hereditary. 
But  it  appears  that  there  may  be  inherited  a  tendency  to  this 
disease,  so  that,  if  exposed,  such  persons  are  more  likely  to 
contract  the  disease  than  those  not  so  predisposed. 

Probably  anything  that  lowers  the  general  vitality  makes 
the  system  more  ready  to  succumb  to  any  of  these  contagious 
diseases.  We  have  all  noticed  what  a  difference  there  is 
among  individuals  in  the  readiness  with  which  they  "  catch  " 
contagious  diseases. 

It  is  believed  by  some  physiologists  that  the  colorless 
blood  corpuscles  may  take  these  germs  of  disease  into  their 
substance,  and  destroy  or  change  them  so  that  the  disease  is 
warded  off.  In  other  words,  they  may  be  compared  to  a  cat 
that  catches  and  eats  the  mice  which  invade  a  house. 

A  good  general  condition  of  the  body  helps  greatly  to  ward 
off  diseases  of  this  nature.  A  cheerful  condition  of  mind  and 
body  should  be  cultivated.  In  times  of  widespread  contagious 
disease,  if  one  is  terrified  into  the  belief  that  he  is  going  to 
have  the  disease,  he  is  more  likely  to  get  it. 

Thorough  cleanliness,  plenty  of  direct  sunshine,  care  in 
diet,  and  the  keeping  of  the  body  in  good  tone,  all  the&e  re- 
duce the  chances  of  "taking"  contagious  diseases. 

An  open-air  life,  abundant  nutritious  food,  freedom  from 
anxiety,  are  probably  the  best  restoratives  for  incipient  eon- 
sumption.  The  Wilderness  Cure  is  a  very  interesting  book, 
by  Marc  Cook  (published  by  Harpers). 

Besides  the  disease-producing   bacteria,  there  are  others 


BACTERIA    OF  PUTREFACTION.  149 

that  cause  decay  and  putrefaction  of  various  kinds.  They 
cause  our  richer  foods  to  "  spoil/'  milk  to  turn  sour,  butter  to 
become  rancid,  etc. 

While  these  bacteria  do  not  cause  disease  in  the  human 
body,  they  often  make  food  poisonous.  The  cases  frequently 
reported  of  poisoning  from  eating  ice-cream,  cheese,  sausage, 
etc.,  are  in  many  cases  due  to  bacteria  in  them.  We  should, 
in  the  first  place,  be  careful  to  get  good,  fresh  foodstuffs.  In 
the  second  place,  it  should  be  so  kept  as  to  prevent  the  intro- 
duction and  development  of  bacteria  in  them.  Bacteria  need 
heat  for  their  growth  (as  we  so  well  know  is  the  case  with 
the  higher  plants).  They  also  need  moisture. 

So  our  principal  modes  of  keeping  foods  from  spoiling  are 
to  keep  them  in  a  cold  place,  or  to  dry  them.  Or  we  heat 
them,  and  then  shut  them  away  from  the  air,  as  in  our  various 
modes  of  canning  and  preserving  foods.  Salting  and  smoking 
meats,  etc.,  preserve  them  by  preventing  the  growth  of  bac- 
teria. Cold  does  not  usually  kill  bacteria.  So,  milk  that  has 
been  kept  in  a  refrigerator,  and  that  seems  sweet,  may  have 
in  it  a  stock  of  bacteria  that  develop  after  we  drink  the  milk, 
from  the  heat  of  our  bodies.  There  are  now  known  ways  of 
killing  the  bacteria  in  milk  and  other  liquids,  known  as  "ster- 
ilizing," that  make  us  safe  from  this"danger. 

When  we  awaken  on  a  cold  winter  morning,  we  are  likely 
to  find  that  the  fire  in  our  hard-coal  stove  has  burned  low. 
Not  enough  heat  is  given  out.  What  is  the  trouble  ?  Is  it 
merely  that  more  coal  is  needed  ?  We  put  another  hod  of 
coal  in  the  magazine  (though  some  usually  remains).  Does 
this  bring  the  desired  result  ?  No.  We  open  the  draft.  Is 
this  sufficient  ?  It  is  not.  We  must  shake  down  the  grate 
and  clean  out  the  clinkers.  The  removal  of  waste  is  often 
more  necessary  than  the  addition  of  a  fresh  supply  of  mate- 
rial. It  is  often  a  more  serious  matter  to  have  the  waste  pipe 


150  NEED   OF  EXCRETION. 

leading  to  the  sewer  clogged,  than  to  have  the  water  supply 
cut  off.  It  is  often  more  to  be  desired  that  the  garbage  cart 
take  away  decaying  matter,  than  that  the  bread  wagon  arrive. 
The  demands  of  nature  for  the  expulsion  of  excreta  are  im- 
perative, while  we  can  withstand  the  cravings  of  hunger  for  a 
while.  So  we  shall  turn  our  attention  for  the  present  to  the 
immediate  demand  for  the  removal  of  wastes,  and  later  con- 
sider the  equally  important,  but  less  importunate,  question  of 
supply  and  renewal. 

READING.  —  (1)  Bacteria,  (2)  Dust  and  Its  Dangers,  (3)  Drink- 
ing Water  and  Ice  Supplies,  Prudden ;  Ventilation  and 
Warming  of  School  Buildings,  Morrison ;  Sanitary  Condi- 
tions of  School-Houses,  Lincoln  (American  Public  Health 
Association) ;  Disinfection  and  Individual  Prophylaxis 
against  Infectious  Diseases,  Sternberg  (American  Public 
Health  Association)  ;  Micro-organisms  and  Disease,  Klein. 


CHAPTER   VI. 


EXCRETION. 
THE    SKIN   AND  ITS    FUNCTIONS. 

WE  have  seen  that  the  energies  of  the  body  —  heat  and 
motion  —  are  produced  by  the  oxidation  in  its  tissues.  Dur- 
ing this  oxidation  waste  products  are  formed,  which  if  retained 
in  the  body  would  cause  very  injurious  effects. 

How  does  the 

body     get     rid     Of  Sweat  Pore 

these  substances  ? 
We  have  already 
learned  that  the 
lungs  throw  off 
carbon  dioxid, 
water,  and  cer- 
tain putmscible 
organic  matter. 

The  skin  is 
constantly  throw- 
ing off  wastes, 
collectively  called 
Sweat,  or  perspi- 
ration. Let  us  first 
study  the  struc- 
ture of  the  skin. 

The  Structure  of  the  Skin.  —  The  skin  has  two  layers, 
the  inner,  or  Dermis,  and  the  outer,  or  Epidermis.  A  bruise 

151 


Hair 
Bulb 


Fig.  50.     Vertical  Section  of  the  Shin. 


152  STRUCTURE  OF  THE  SKIN. 

often  loosens  or  breaks  off  a  piece  of  the  epidermis,  but  seldom 
removes  the  derm  is.  The  epidermis  is  thick  over  the  palma 
of  the  hands  and  soles  of  the  feet ;  elsewhere  it  is  thin. 
Not  often  seeing  the  whole  thickness  of  the  skin,  we  do  not 
easily  get  an  idea  of  its  real  thickness.  The  skin  constitutes 
about  one-fifteenth  of  the  body's  weight,  and  if  tanned,  makes 
a  moderately  firm  and  thick  leather  very  much  resembling  the 
pigskin  used  for  covering  footballs,  striking-bags,  etc. 

The  epidermis  consists  of  many  layers  of  cells  packed 
closety  together.  The  deepest  cells  may  be  compared  to 
grapes  with  their  cell  walls  plumply  filled  out  by  the  liquids 
of  the  cell.  Suppose,  for  the  inner  layer,  grapes  set  on  end, 
and  so  closely  packed  together  as  to  press  each  other  into 
elongated  prisms.  Then  layers  less  closely  pressed,  more 
nearly  spherical ;  then  layers  of  cells  with  less  liquid  in  them, 
and  somewhat  shrunken,  like  raisins ;  then  still  dryer  cells, 
flattened  parallel  with  the  surface  of  the  skin  ;  and  last,  in  the 
outer  part,  layers  of  cell  walls,  dry  and  empty,  pressed  flat 
like  empty  grapeskins.  The  flat  cell  walls  come  off  in  flakes 
(called  dandruff  from  the  scalp)  from  all  the  surface  of  the 
skin,  and  new  cells  are  continually  formed  in  the  deeper 
layers,  while  the  old,  dry,  dead  cells  are  continually  thrown 
off  from  the  outer  surface. 

The  Pigment,  or  coloring  matter,  which  gives  color  to  the 
skin,  lies  in  the  deeper  layers  of  the  epidermis.  In  albinos 
this  is  wanting ;  in  persons  having  a  fair  skin  it  is  small  in 
amount,  in  dark  skins  more  abundant.  Where  the  pigment 
is  irregularly  scattered,  it  causes  freckles,. etc. 

A  blister  is  caused  by  separating  the  outer,  harder  layer 
of  the  epidermis  from  the  inner,  softer,  darker  layer  of  the 
epidermis,  as  shown  at  B  in  Fig.  50.  Serum,  or  blood,  fills 
the  space  between  the  separated  layers. 

The  dermis  consists  chiefly  of  tough  fibers,  interlacing  in 


THE  EPIDERMIS. 


153 


all  directions,  somewhat  like  felt,  hence  the  strength  and 
durability  of  leather,  which  is  the  dennis  preserved  and  pre- 
pared in  various  ways.  The  epidermis  is  usually  removed  in 
tanning. 

The  outer  surface  of  the  dennis  has  numerous  conical  ele- 
vations, Papillae,  which  fit  into  corresponding  depressions  in 

Mouth  of  Sweat  Duct 


Papilla 


"~  Dermis 

v 

Vein         Artery 

Fig.  51.    Section  of  Epidermis,  Showing  Papilla.    (Highly  Magnified.) 

the  epidermis.  In  the  palm  of  the  hand,  etc.,  the  ridges  of 
the  epidermis  correspond  to  the  rows  of  papillae  of  the  dermis 
underneath.  But  over  most  of  the  dermis  the  papillae  are 
irregularly  placed,  and  there  are  no  corresponding  elevations 
of  the  epidermis. 


154  THE  SWEAT   GLANDS. 

The  dermis  is  richly  supplied  with  blood  capillaries  and 
with  lymph  capillaries,  but  the  epidermis  has  neither.  Each 
papilla  is  abundantly  supplied  with  blood,  having  its  own  net- 
work of  capillaries. 

Hairs  and  nails  are  outgrowths  of  the  epidermis.  Their 
deeper  parts  are  embedded  in  the  dermis,  through  which, 
from  the  blood,  they  derive  their  nourishment ;  thus,  like  the 
epidermis  itself,  they  are  dead  in  the  outermost  part,  and 
these  parts  are  supplied  by  growth  from  beneath. 

The  Sweat  Glands.  —  A  model  of  a  cross-section  of  the 
skin,  showing  the  glands,  hairs,  etc.,  is  very  helpful. 

The  sweat  glands  are  minute  tubes  whose  inner  ends  are 
closed,  and  whose  outer  ends  open  upon  the  surface  of  the 
skin.  Place  a  linen  tester  on  the  palm  of  the  hand,  and  note 
the  openings  of  the  ducts  of  the  sweat  glands,  or  sweat  pores. 
Count  the  pores  within  the  square  shown.  Measure  this 
square,  and  then  estimate  the  number  of  sweat  glands  to  a 
square  inch  of  the  palm.  The  tube  going  inward  pursues  a 
corkscrew-like  course  through  the  epidermis,  then  becomes 
straighter,  and,  having  passed  through  the  dermis,  is  coiled  up 
in  a  ball  in  the  connective  tissue  lying  just  underneath  the 
inner  skin.  We  can  fairly  well  represent  this  gland  as  fol- 
lows :  Take  a  small  rubber  tube,  say  one  foot  long ;  close  one 
end ;  tie  the  half  with  the  closed  end  into  a  globular  knot ; 
around  and  between  the  coils  place  a  network  of  red  cord  to 
represent  -the  blood  capillaries,  as  there  is  a  rich  supply  of 
these  blood  tubes  around  the  coil.  The  cells  forming  the 
walls  of  the  coiled  part  differ  from  those  of  the  Duct,  or 
straighter  part  of  the  tube.  As  the  blood  flows  around  the 
coil,  it  gives  off  lymph ;  and  from  the  lymph  the  cells  of  the 
gland  take  certain  waste  matters,  which  are  passed  out  to 
the  surface  of  the  skin.  There  is  also  some  muscular  tissue 
around  the  walls  of  the  gland. 


ESSENTIALS   OF  A    GLAND. 


155 


The  sweat  tube  is  the  first  example  we  have  had  of  a  Gland. 
The  essential  features  of  a  gland  are  :  - 

1.  Cells   lining  a   cavity,    the  cells    having  the    power  of 
taking  something  from  the  blood  (or  lymph). 

2.  Blood  supply  or  lymph  supply. 

3.  A  tube  or  Duct  to  pour  out  on  some  surface  the  liquid 
taken  from  the  lymph. 

4.  Nerves  to  the  cells  by  which  their  action  is  controlled. 


Epithelium,  or  Epidermis. 


Compound  Glanc 
Fig.  52.     Evolution  of  Glands.     (After  Landois  &  Stirling.) 

5.  (Probably)  Special  nerve  centers  controlling  the  various 
glands.  The  cells  of  the  glands  in  many  cases  so  alter  the 
substances  taken  from  the  blood  that  what  is  produced  by  the 
gland  differs  from  anything  found  in  the  blood.  The  gland 
may  be  said  to  manufacture  the  liquid  it  gives  off. 

The  sweat  glands,  like  all  glands,  are  largely  dependent  on 


156  COMPOSITION   OF  SWEAT. 

the  amount  of  blood  supply.  In  exercising,  the  skin  is  usually 
redder  from  the  greater  blood  supply,  and  at  the  same  time 
the  glands  are  more  active,  as  they  should  be;  for,  during 
exercise,  and  immediately  after  it,  there  is  more  waste  matter 
to  be  thrown  out.  But  the  activity  of  the  gland  is  not  a 
mere  filtering  process,  due  to  the  greater  blood  pressure. 
There  may  be  a  cold  sweat ;  i.e.,  when  the  skin  is  pale.  Here 
is  evidence  that  the  activity  of  the  glands  is  primarily  due 
to  nerve  impulses  from  some  nerve  center  to  the  gland  cells. 

The  sweat  glands  rid  the  body  of  certain  waste  matters 
that  can  no  longer  be  used.  They  are  Excretory  glands.  In 
structure  they  are  Simple  glands. 

The  sweat  glands  are  thickly  distributed  over  the  whole 
surface  of  the  body,  but  are  especially  numerous  and  large  on 
the  palm  of  the  hand  and  the  sole  of  the  foot.  In  the  arm- 
pit the  glands  are  very  large. 

The  Oil  glands  of  the  skin  are  distributed  over  all  the  sur- 
face except  the  palms  of  the  hand  and  soles  of  the  feet.  The 
oily  matter  is  usually  poured  out  around  the  hairs  as  they 
emerge  from  the  skin.  It  serves  to  oil  the  hair  and  the  skin, 
and  keep  them  from  becoming  too  dry. 

Composition  and  Amount  of  Sweat.  —  Sweat  is  mostly 
water ;  about  one  per  cent  is  solid  matter,  including  salt  and 
certain  matters  which,  like  the  organic  waste  matter  from  the 
lungs,  easily  putrefy,  and  some  oily  matter  from  the  oil  glands 
of  the  skin. 

Thrust  the  hand  into  a  glass  jar,  preferably  a  jar  that  has 
been  in  a  cool  place.  Note  the  moisture  that  soon  gathers  on 
the  inside  of  the  jar  from  the  insensible  sweat  of  the  hand. 
A  common  fruit-jar  will  do  for  a  small  hand ;  but  a  candy-jar 
is  better,  having  a  larger  mouth  and  clear  glass. 

Ordinarily  the  sweat  is  evaporated  as  fast  as  it  is  poured 
out  j  in  distinction  from  this  insensible  perspiration  it  is 


FUNCTIONS   OF  THE  SKIN.  157 

called  sensible  perspiration  when  it  accumulates  enough  to 
be  perceptible. 

The  amount  of  perspiration  is  about  one  quart  in  twenty- 
four  hours. 

The  amount  varies  with  :  — 

1.  Temperature,  dryness,  and  rate  of  renewal  of  air. 

2.  Condition  of  the  blood ;  e.g.,  if  watery  from  drinking 
much  water. 

3.  Muscular  exercise. 

4.  Certain  drugs  —  some  exciting  perspiration ;  e.g.,  cam- 
phor :  others  diminishing  it ;  e.g.,  belladonna. 

5.  The  nerves  exercise  great  influence  on  the  activity  of 
the  cells  of  the  gland. 

The  Functions  of  the  Skin.  —  1.  Protective,  (a)  As  a 
tough  covering,  (b)  As  aided  by  the  oil  from  the  oil  glands. 

2.  Excretory,      (a)    Giving  off  sweat.      (V)    Also  a  little 
carbon  dioxid. 

3.  Absorptive,     (a)    Oxygen,  to  a  slight  amount,  may  be 
taken,  (&)  and  medicine  (rubbing  in  ointments). 

4.  Sensory  —  organ  of  touch. 

5.  Heat-regulating. 

Next  to  its  excretion,  the  heat-regulation  by  the  skin  is  the 
most  important  for  our  present  consideration. 

Regulation  of  the  Temperature  of  the  Body  by  the 
Skin.  —  It  is  a  striking  fact  that,  except  in  disease,  the  tem- 
perature of  the  body  varies  only  a  little  from  98.5°  F.  in  sum- 
mer and  winter,  during  exercise  and  rest.  The  rate  of  heat- 
production  varies  greatly.  The  rate  of  giving  off  heat  must 
therefore  vary  accordingly.  Otherwise  the  temperature  of  the 
body  would  soon  reach  the  boiling-point  (in  thirty-six  hours)  ; 
and,  as  the  body  is  largely  composed  of  water,  it  would  be 
cooked,  and  part  of  it  disappear  as  invisible  gas.  But  long 
before  reaching  212°  F.  the  tissues  would  be  killed. 


158  REGULATION  OF  BODILY  HEAT. 

In  considering  the  regulation  of  the  body's  temperature, 
we  must  bear  in  mind  that  the  body  is  surrounded  by  air 
almost  always  considerably  cooler  than  itself.  The  body  is, 
therefore,  almost  always  giving  off  heat.  Our  clothes  do  not 
warm  us:  we  warm  them,  and  they  keep  us  from  warming 
the  air  too  fast ;  i.e.,  keep  us  from  losing  too  much  heat.  In- 
door air  in  winter  in  the  cooler  parts  of  the  United  States  is 
kept  at  about  70°  F.  by  artificial  heat.  This  air  does  not 
warm  us.  We  being  about  30°  F.  warmer,  are  warming  it. 

The  skin  gives  off  heat  by  :  — 

1.  Radiation  :  heat  is  given  off  in  every  direction. 

2.  Conduction :  whatever  we  touch  that  is  cooler  than  our 
bodies  is  warmed.     We  warm  chairs,  beds,  clothing,  etc. 

3.  The  air  in  contact  with  the  skin  is  warmed  and  rises. 
Our  body's  heat  is  thus  carried  off  by  Convection. 

4.  The  sweat  leaving  the  body  is  warm ;  i.e.,  it  takes  away 
heat  with  it. 

5.  But  the  Evaporation  of  the  sweat  is  a  much  more  im- 
portant factor  in  heat-regulation.     Any  liquid,  in  evaporating? 
absorbs  heat.     The  cooling  effect  of  alcohol  or  ether  on  the 
skin  is  due  to  the  fact  that  heat  is  taken  from  the  body  in 
converting  the  liquid  into  a  gas. 

Let  the  teacher,  with  a  medicine-dropper,  place  a  drop  of 
ether  or  cologne  on  the  back  of  the  hand  of  each  pupil. 

When  we  put  cologne  (or  alcohol  or  ether)  on  the  hand  or 
face,  we  notice  two  facts :  (1)  It  produces  a  cooling  effect. 
(2)  The  liquid  soon  disappears.  To  prove  that  it  is  not 
merely  that  the  liquid  is  cool,  try  the  following :  Tie  a  piece 
of  cheesecloth  around  the  bulb  of  a  thermometer;  dip  the 
bulb  into  a  dish  of  alcohol  or  ether,  and  note  its  temperatiire 
(if  these  are  not  at  hand,  gasoline  serves  very  well,  or  even 
water,  though  the  evaporation  is  slower)  ;  then  lift  the  bulb 
out  of  the  liquid,  and  note  any  change  in  temperature.  The 


DISTRIBUTION   OF  HEAT.  159 

evaporation  of  the  liquid  takes  heat  from  the  bulb,  and  causes 
the  thermometer  to  register  a  lower  temperature.  We  sponge 
the  face  and  hands  of  a  feverish  patient  to  reduce  the  amount 
of  heat.  We  sprinkle  the  floor  in  hot  weather,  and,  by  the 
absorption  of  heat  in  evaporating  the  water,  cool  the  air  of 
the  room. 

When  we  exercise,  we  produce  more  heat ;  we  sweat  more ; 
more  heat  is  taken  from  the  body  to  evaporate  this  greater 
amount  of  sweat.  If  we  are  not  exercising,  and  are  in  cooler 
air,  we  sweat  less,  and  less  heat  is  given  off. 

This  should  also  be  observed :  When  we  exercise,  more 
blood  is  in  the  skin,  and  more  heat  is  given  off  in  the  other 
ways  mentioned ;  when  we  exercise  less,  the  skin,  especially 
in  a  cool  air,  becomes  paler,  —  i.e.,  has  less  blood  in  it,  and 
heat  is  economized. 

Of  the  total  amount  of  heat  given  off  by  the  body,  eighty- 
seven  hundredths  are  given  off  by  the  skin ;  most  of  the  rest 
is  given  off  by  the  lungs ;  a  small  amount  is  given  off  by  the 
urine,  feces,  etc. 

Distribution  of  Heat  in  the  Body.  —  If  more  heat  is 
produced  in  one  part  of  the  body  than  in  the  others,  the  cir- 
culation of  the  blood  tends  to  equalize  the  temperatures  of  the 
different  parts.  So,  too,  if  one  part  is  cooled,  —  that  is,  is  los- 
ing heat  faster  than  the  others,  —  the  blood  brings  heat  from 
other  organs  to  that  part.  For  instance,  if  one  holds  his  hands 
in  the  snow,  or  puts  a  piece  of  ice  on  his  wrist,  the  whole  blood- 
stream is  cooled.  So  if  the  hands  and  the  feet  are  exposed  to 
the  cold,  it  may  do  little  good  to  have  the  rest  of  the  body 
covered.  A  pair  of  wristers  and  a  pair  of  leggings  or  gaiters 
may  often  add  more  to  one's  comfort  than  a  heavy  overcoat. 

Regulation  of  the  Production  of  Heat  in  the  Body. 
— -We  have  just  considered  how  the  temperature  of  the  body 
may  be  made  uniform  by  regulating  the  amount  of  heat  given 


160  REGULATION   OF  HEAT  PRODUCTION. 

off.  But  this  is  not  the  only  fact  to  be  taken  into  considera- 
tion. It  seems  highly  probable  that  there  is  a  nerve  center 
controlling  the  amount  of  heat  produced.  We  know  that  the 
heat  is  produced  by  oxidations  in  the  tissues.  Now,  the  effect 
of  cold  is  to  increase  the  amount  of  oxygen  consumed  and 
the  amount  of  carbon  dioxid  given  off,  showing  that  more 
heat  has  actually  been  generated. 

We  call  certain  animals  "  cold-blooded."  But  the  fact  that 
they  are  less  warm  than  birds  and  mammals  is  not  so  signifi- 
cant as  the  fact  that  these  cold-blooded  animals,  instead  of 
maintaining  a  constant  temperature,  vary  greatly  in  tempera- 
ture, being  ordinarily  only  a  little  warmer  than  the  surround- 
ing air  or  water.  Now,  when  these  creatures  are  cold,  they 
take  less  oxygen  and  give  off  less  carbon  dioxid. 

Aside  from  these  natural  methods  of  keeping  the  tempera- 
ture of  the  body  uniform,  we  aid  the  process  in  more  or  less 
artificial  ways. 

Regulation  of  Bodily  Temperature  by  Food  and 
Clothing.  —  When  subject  to  the  influence  of  cold  we  choose 
more  heat-producing  foods,  as  fatty  foodstuffs ;  we  take  more 
vigorous  exercise ;  we  put  on  more  clothing,  and  especially  of 
the  non-conducting  kinds,  —  woolens.  In  warmer  weather  we 
eat  less  fatty  matter,  wear  less  clothing,  and  are  less  disposed 
to  exercise  actively ;  we  fan  ourselves  to  help  get  rid  of  heat ; 
we  take  ices  and  cold  drinks.  For  most  persons  it  seems 
better  to  wear  woolen  most  of  the  time,  as  even  in  summer 
we  are  subject  to  sudden  changes  in  the  air,  and  with  such 
covering  one  is  less  likely  to  take  cold. 

In  getting  the  clothing  wet,  the  greater  loss  of  heat  is  not 
from  the  coolness  of  the  water,  but  the  loss  of  heat  in  evapo- 
rating the  water  from  the  clothing ;  and  this  goes  on  for  a  long 
time.  Of  course  it  is  very  desirable  to  put  on  dry  clothing  as 
soon  as  possible ;  but  a  person  in  good  health  is  not  very 


THE  KIDNEYS.  161 

likely  to  take  cold,  except  in  very  cold  weather,  if  he  contin- 
ues active  exercise  till  he  can  change  the  wet  garments  for 
dry  ones.  Children  do  not  often  take  cold  from  wading  in 
water  so  long  as  they  are  barefooted ;  but  if  they  get  the 
shoes  and  stockings  wet,  they  are  likely  to  take  cold,  for  the 
reasons  above  given.  Many  persons  make  a  mistake  in  chan- 
ging their  winter  underwear  for  summer  too  early.  In  most 
of  the  Northern  States  it  is  not  usually  wise  to  do  so  until  the 
first  of  June ;  but  of  course  no  definite  rule  can  be  laid  down 
in  this  matter. 

Sunshine.  —  For  good  health  we  need  sunshine.  Of  course 
we  get  sunlight  indoors,  but  so  do  many  plants  that  drag  out 
a  sickly  existence.  We  need  direct  sunlight  (when  it  is  not 
too  hot),  and  many  an  invalid  has  been  cured  by  sun-baths. 
Part  of  the  beneficial  effects  of  sea-bathing  is  due  to  sunshine. 
It  is  a  good  thing  that  it  is  now  the  fashion  to  take  a  vacation 
and  get  well  tanned.  One  of  the  benefits  of  the  resorts  of 
Colorado  (in  addition  to  the  climate's  mildness)  is  that  there 
are  very  few  cloudy  days  during  the  year. 


THE    KIDNEYS. 

One  important  part  of  the  work  of  the  lungs,  as  we  have 
seen,  is  to  throw  out  carbon  dioxid.  The  skin  also  throws  off 
certain  wastes.  The  kidneys  have  the  special  task  of  excret- 
ing a  waste  product  of  the  body  called  Urea.  Urea  is  the 
nitrogen-containing  waste. 

The  kidneys  are  attached  to  the  dorsal  wall  of  the  abdom- 
inal cavity.  The  depression  of  the  kidneys  corresponding 
to  the  stem  scar  on  a  bean  is  called  the  Hilum.  From  the 
hilum  issues  a  white  tube,  the  Ureter,  which  conveys  the 
urine  to  the  bladder.  Entering  the  kidney  alongside  the  ureter 


162  DISSECTION  OF  THE  KIDNEY. 

is  the  Renal  Artery,  a  branch  of  the  aorta ;  and  from  near  the 
same  point  the  Renal  Vein  returns  the  blood  from  the  kidneys, 
and  pours  it  into  the  postcaval  vein.  Through  the  kidneys  is 
pouring  a  continuous  stream  of  blood,  varying  in  amount  at 
different  times  and  in  different  conditions. 

The  kidney  receives  a  very  large  amount  of  blood  for  its 
size,  as  compared  with  other  organs.  The  flow  to  it  is  made 
easy  by  the  fact  that  the  renal  arteries  are  relatively  wide 
and  short,  and  take  the  blood  directly  from  the  main  current 
of  the  aorta. 

When  in  active  work  the  kidney  is  distended  with  blood. 
The  dead  kidney,  as  we  study  it,  is  smaller  than  during  life, 
just  as  the  dead  heart  is  considerably  smaller  than  when  alive. 

From  the  kidney,  through  the  ureter,  Urine  is  continually 
passing  to  the  bladder.  Urine  is  mostly  water,  containing 
urea,  salt,  and  various  other  substances  in  small  amounts. 
Urea  is  a  waste  matter  brought  in  the  blood.  If  the  kidneys 
are  stopped  in  their  action,  urea  accumulates  in  the  blood, 
and  death  soon  results;  to  just  the  degree  that  the  kidneys 
fail  in  performing  their  duty,  just  so  far  must  the  body  suffer. 
Let  us  study  the  structure  of  the  kidney,  that  we  may,  in  part 
at  least,  understand  its  action. 

For  dissection,  the  sheep's  kidney,  being  a  little  more  simple 
in  structure,  is  preferable;  but  a  pig's  kidney  is  more  closely 
like  that  of  man. 

Dissection  of  the  Kidney.  —  A  class  can  usually  be 
supplied  by  asking  the  butchers  a  week  or  two  beforehand  to 
save  them;  or,  if  near  a  large  slaughtering-house,  pigs'  kid- 
neys can  easily  be  obtained.  Butchers  do  not  like  to  remove 
the  kidneys  from  the  sheep's  carcass  until  it  is  cut  up. 

1.  Observe  the  depression  in  the  inner  border  of  the  kidney, 
the  Hilum. 

2.  From  the  hilum  trace  the  slender  white  tube,  the  Ureter, 


MINUTE  STRUCTURE  OF  KIDNEY.  163 

back  to  the  bladder.     Find  also  the  renal  artery  and  vein, 
branching  as  they  enter  the  kidney  through  the  hilum. 

3.  With  a  sharp  knife  split  the  kidney  like  a  bean,  begin- 
ning at  the  outer  border,  stopping  the  cut  when  the  cavity, 
lined  by  a  white  membrane,  is  reached  near  the  hilum.     With 
forceps  pry  about  to  explore  the  cavity  bounded  by  this  white 
membrane.     Note  the  branches  of  the  cavity  into  the  kidney. 
Note  also  the  extension  of  the  white  membrane  into  these 
cavities.     Make   out  that  the  blood  vessels  extend  through 
these  white  branches  to  the  outer  part  of  the  kidney.     Count 
these  branches. 

4.  In  the  center  of  the  white  membrane  find  the  opening 
of  the  ureter,  through  which  the  urine  is  conveyed  to  the 
bladder.     Pass  a  probe  through  this  opening  into  the  ureter. 

5.  Note  the  difference   in  color  of   the   outer  and   inner 
parts  of  the   kidney.     At  the  line  of   change  of  color  find 
where  the  blood  tubes  first  branch  into  the  real  kidney  sub- 
stance.    Examine  carefully  the  cut  surface  of  the  kidney,  to 
see  its  markings. 

6.  Make  a  drawing  of  one-half  of  the  kidney  as  seen  from 
the  inside,  showing  the  above  points. 

7.  Cut  across  the  middle  of  the  kidney  at  right  angles  to 
its  length,  and  make  a  drawing  of  the  cross-section.     The  pro- 
jection of  the  kidney  substance  into  the  cavity  opposite  the 
ureter  is  the  Urinary   Pyramid,   and   from  its  apex,  through 
many    fine    holes,   issues    the    urine    which   the    kidney   has 
secreted  from  the  blood. 

Microscopic  Structure  of  the  Kidney.  —  If  microscopic 
sections  of  the  kidney  are  at  hand  they  should  be  examined ; 
but  the  kidney  is  so  complicated  in  structure  that  a  diagram 
is  needed  in  connection  with  the  sections  and  the  descriptions. 
The  unit  of  structure  in  the  kidney  is  a  tube  which  takes 
material  from  adjacent  blood  capillaries.  The  relation  of  the 


164 


STRUCTURE  OF  THE  KIDNEY. 


Cavity  of 
Kidney 


capillaries  to  the  tube  is  peculiar.  The  inner  end  of  the  tube 
is  enlarged  into  a  ball ;  this  ball  is  deeply  depressed  opposite 
the  point  where  the  tube  leaves  it.  Into  this  depression  is 
fitted  a  globular  tuft  of  capillaries.  The  arrangement  may  be 
illustrated  by  the  common  toy  known  as  the  "  cup  and  ball." 
The  handle  of  the  cup  should  be  hollow  to  represent  the  tube ; 

the  cup  should  be  double- 
walled,  the  space  between 
the  inner  and  outer  layers 
continuous  with  the  hollow 
of  the  handle.  Instead  of 
a  solid  ball  held  by  one 
string,  there  should  be  a 
yarn  ball  with  two  large 
strings  attached  to  one 
side,  one  representing  the 
artery,  the  other  the 
vein  j  the  yarn  ball 
represents  the  dense 
cluster  of  capilla- 
ries. A  still  better 
illustration  of  the  urinary 
tube  and  capsule  may  be 
made  thus :  Take  a  thistle  tube  (used  in  the  chemical  labora- 
tory), let  down  into  the  bulb  a  rubber  balloon  or  bag  of  sheet- 
rubber  or  cloth,  fastening  the  margin  around  the  rim  of  the 
bulb;  put  a  little  ball  of  red  yarn  in  the  depression ' of  the 
bag  hanging  in  the  bulb ;  have  two  ends  of  the  yarn  project- 
ing to  represent  the  artery  entering  and  the  vein  leaving  the 
capsule.  The  vein,  soon  after  it  emerges,  breaks  up  into 
another  set  of  capillaries  which  extend  around  the  tube.  A 
number  of  these  primary  tubes  unite,  and  many  of  the  com- 
mon ducts  open  at  the  apex  of  each  of  the  urinary  pyramids, 


Ureter 
Fig.  53.     Cross  Section  of  Kidney. 


SKIN  AND  KIDNEYS. 


165 


emptying  their  secretion  into  the  cavity  of  the  kidney.  As 
the  blood  flows  through  the  tuft  of  capillaries  in  the  Capsule 
at  the  end  of  the  tube,  a  good  deal  of  water,  together  with  salt 
and  some  other  substances,  passes  through  the  thin  partition 
into  the  cavity  of  the  capsule,  and  thence  down  the  tube.  The 
walls  of  the  tube  are  thicker  than,  and  its  cells  are  different 
from,  those  of  the  capsule.  These  cells  take  the  urea  and 
some  other  substances  from  the  blood,  and  pass  them  into  the 
tube  to  join  the  more  watery  material  from  the  capsule. 

Comparison  of  the  Skin  and  the  Kidneys.  —  The  kid- 
neys, then,  are  not  very  different  from  the  skin.  Imagine  a 
piece  of  skin  rolled  up 
with  its  outer  surface 
turned  inward.  Its  glands 
then  would  pour  their  se- 
cretions into  a  cavity  where 
they  might  accumulate  in- 
stead of  evaporating  as 
fast  as  they  are  poured 
out.  Of  course  the 
kidneys  have  a 


Urinary  Capsule 


Artery 


Vein 


somewhat  different 
work  from  the  skin, 
but  in  its  general 
plan  of  working  we 
might  say  they  are  skin 
turned  outside  in.  The 
kidney  unit  (the  tubular 
gland)  has  branches ;  i.e.,  is  compound.  The  kidney  is  a  com- 
pound gland  of  excretion,  internal  in  position.  Both  skin  and 
kidneys  excrete  a  good  deal  of  water,  with  salt  and  some 
other  matter  in  common.  There  is  a  very  immediate  relation 
between  the  work  of  the  kidneys  and  that  of  the  skin.  In 


Urinary,  Tube 
Fig.  54.     Urinary  Cone,  Enlarged.     (Diagram.) 


166  SKIN  AND  KIDNEYS. 

warm  weather,  and  when  exercising  actively,  we  perspire 
freely,  and  the  amount  of  urine  is  reduced;  when  we  exer- 
cise less,  and  especially  in  cold  weather,  we  perspire  less, 
and  the  urine  is  more  abundant.  Cold  drives  the  blood  from 
the  surface.  Consequently  more  blood  goes  to  the  kidneys 
(as  well  as  to  the  other  internal  organs),  and  they  throw  off 
much  more  water,  though  probably  little  if  any  more  urea. 
The  average  daily  amount  of  urine  is  about  three  pints.  The 
quantity  is  increased  by  high  blood  pressure,  copious  drinking, 
by  cold  air  (driving  the  blood  from  the  skin),  nitrogenous 
food,  certain  drugs,  etc.  It  is  diminished  by  a  lowered  blood 
pressure,  profuse  sweating,  diarrhea,  non-nitrogenous  food, 
some  diseases  of  the  kidneys,  etc. 

The  blood  leaving  the  kidney,  especially  when  in  full 
activity,  is  still  bright  red ;  it  is  probably  the  purest  blood  in 
the  body. 

What  is  the  effect  of  all  the  processes  thus  far  studied  on 
the  weight  of  the  body  ? 

READING.  —  The  Skin  and  its  Troubles,  D.  Appleton  &  Co. 


CHAPTER  VII. 

DIGESTION. 
FOOD  AND  COOKING. 

THUS  far  we  have  been  studying  processes  by  which  the 
body's  weight  is  reduced.  We  have  studied  the  oxidation 
in  the  tissues  and  the  removal  of  the  wastes.  Unless  the 
tissues  receive  a  corresponding  supply,  the  heat  and  energy 
of  the  body  cannot  long  be  maintained. 

All  substances  that  go  to  make  up  the  tissues  or  produce 
energy  are  Foods.  Certain  substances  that  do  not  become 
part  of  any  tissues,  nor  in  themselves  produce  energy,  are 
useful  in  aiding  the  processes  going  on  in  the  body.  These 
may  be  called  Accessory  Foods,  e.g.,  condiments ;  some  acces- 
sory foods,  such  as  coffee,  seem  to  retard  the  waste  of  tissues. 

Poods  and  Foodstuffs.  —  Most  of  our  articles  of  food 
consist  of  two  or  more  different  kinds  of  materials.  For  in- 
stance, milk  consists  (1)  chiefly  of  water ;  in  this  are  (2)  the 
substance  that  makes  cheese  (casein)  ;  (3)  cream,  from  which 
we  get  butter  (fat)  ;  (4)  sugar,  which  gives  milk  a  sweet  taste  , 
(5)  salts,  such  as  common  salt,  lime  salts,  etc.  These  differ- 
ent materials  are  Foodstuffs.  We  have  many  kinds  of  foods 
but  few  foodstuffs,  which  we  find  occurring  over  and  over 
again,  in  various  forms,  in  the  numerous  things  we  eat. 

Foodstuffs  are  also  called  "alimentary  principles,"  " nutri- 
tive principles,"  "proximate  principles,"  "  food  substances,"  etc. 

The  foodstuffs  are  classified  into  :  — 

1.  Proteids  (example,  casein). 

2.  Fats. 

167 


168  FOODSTUFFS. 

3.  Carbohydrates  (example,  sugar). 

4.  Water. 

5.  Salts. 

(6.  Oxygen  is  by  some  authors  called  a  food,  but  it  is 
more  convenient  to  treat  of  it  elsewhere.) 

The  Proteids.  — The  chief  substance  in  the  white  of  an 
egg  is  Albumen,  a  typical  proteid.  Of  the  many  proteids, 
some  of  the  more  commonly  known  are  Casein  (the  curd  of 
milk),  Gluten  (in  grains),  Legumin  (in  peas  and  beans),  Fibrin 
(in  blood),  Myosin  (in  muscles).  Gelatin  (obtained  from  con- 
nective tissue  and  bones  by  prolonged  boiling)  differs  con- 
siderably from  the  proteids  in  composition,  but  may  be 
counted  in  with  them.  It  is  less  valuable  as  a  food  than  the 
true  proteids,  although  in  certain  circumstances  more  desi- 
rable from  the  fact  that  it  is  very  easily  digested. 

The  proteids  are  — 

1.  Composed  of  carbon,  hydrogen,  oxygen,  and  nitrogen, 
with  a  little  sulphur,  and,  in  some,  traces  of  phosphorus. 

2.  Jelly-like,    and  do  not   easily  diffuse  through  animal 
membranes  (a  characteristic  to  be  kept  in  mind  when  study- 
ing digestion). 

3.  Coagulable  (usually)  by  heat,  acids,  alcohol,  etc. 

4.  Easily  putrefy  when  moist  and  warm. 

The  proteids  are  of  special  importance  as  foods  because 
the  most  active  tissues,  muscular,  nervous,  and  glandular,  and 
the  most  important  liquids  of  the  body,  e.g.,  blood  and  lymph, 
have  proteid  as  a  chief  constituent.  Proteid  food,  therefore, 
must  be  taken  to  make  good  the  losses  of  these  tissues  during 
their  oxidations. 

Proteid-Containing  Foods.  —  Lean  meat  has  about 
twenty  per  cent  of  proteid,  the  rest  being  chiefly  water. 
Beef  and  mutton  are  more  easily  digested  than  veal  and  pork. 
(For  a  comparison  of  fat  and  lean  meat,  see  Appendix.) 


PROTEID   FOODS.  169 

People  who  cannot  afford  to  buy  tenderloin  may  take  some 
comfort  in  knowing  that  there  is  really  more  nourishment 
in  a  round  steak. 

Fish,  when  fresh,  is  a  good  food.  Although,  as  a  rule, 
salted  meats  are  less  easily  digested  than  fresh,  salted  cod- 
fish is  a  nourishing  and  economical  food. 

Eggs  contain  considerable  proteid,  but  their  value  as  food 
has  been  overrated.  The  yolk  has  a  large  amount  of  fat. 
(See  Appendix.)  Although  the  egg  has  all  the  material 
needed  to  form  a  chick,  it  is  not  a  perfect  food  for  man. 

Milk,  as  we  have  seen,  is  an  ideal  food  in  that  it  contains 
all  the  kinds  of  foodstuffs,  and  in  the  right  proportion  for  the 
young  mammal.  But  the  proportions  are  not  right  for  the 
adult.  An  adult  would  need  four  quarts  and  a  half  daily, 
and  then  he  would  not  get  enough  carbohydrates  (represented 
in  milk  by  the  sugar). 

CHEESE.  —  Cheese  is  very  rich  in  proteid,  much  more  so 
than  lean  meat.  Yet,  as  it  is  rather  difficult  of  digestion  we 
do  not  use  it  largely  as  food  ;  we  regard  it  more  as  a  luxury, 
while  in  many  parts  of  Europe  it  is  largely  used  as  food, 
taking  the  place  of  meat.  It  is  a  cheap  food,  and  might 
well  be  used  more  extensively,  especially  by  laboring  men. 
It  is  stated  that  when  taken  with  milk  it  is  more  readily 
digested. 

VEGETABLE  PROTEIDS.  —  Peas  and  beans  (dried)  contain  as 
much  proteid  (legumin)  as  meat,  and  all  the  cereals  contain 
some  proteid  (gluten). 

Fats.  —  Fats  are  composed  of  carbon,  hydrogen,  and  oxy- 
gen. The  oxygen  is  small  in  amount,  so  these  foods  yield 
a  great  amount  of  energy  by  the  oxidation  of  their  carbon 
(forming  carbon  dioxid)  and  hydrogen  (forming  water).  (For 
further  properties  of  the  fats  and  their  importance  as  food, 
see  Appendix). 


170  FATS  —  CAEBOHYD11A  TES. 

The  Carbohydrates  and  Carbohydrate  -  Containing 
Foods.  —  Sugar  and  starch  are  the  chief  carbohydrates. 

Wheat  and  the  grains  are  chiefly  starch  (excepting  water, 
which  makes  up  the  larger  part  of  nearly  all  foods),  with  a 
small  amount  of  proteid  (gluten)  and  a  very  little  fat. 

In  ordinary  white  flour  nearly  all  the  gluten  has  been  re. 
moved  with  the  bran  or  "  middlings."  While  wheat,  or  breac 
made  from  the  whole  grain  of  the  wheat,  may  support  life, 
one  would  starve  if  he  attempted  to  live  on  common  white 
bread  alone.  It  is  almost  entirely  starch.  In  the  "Entire 
Wheat  Flour"  it  is  claimed  that  all  the  gluten  is  retained, 
only  the  very  thin  outer  husk  of  the  grain  being  removed. 
It  does  not  make  so  white  a  flour,  but  it  is  better  adapted  to 
use  as  a  food.  If  we  use  white  bread,  having  thrown  away 
the  nitrogenous  part  of  the  wheat,  we  need  to  take  more  pro- 
teid from  other  sources  than  if  we  used  the  entire  wheat 
flour.  This  is  not  economy.  And  it  is  claimed  that  the  entire 
wheat  bread  is  more  wholesome  as  well  as  more  nutritious. 
The  part  thrown  away  has  in  it  phosphates  as  well  as  the 
nitrogenous  material.  This  flour  is  ground  fine,  so  that  it  has 
not  the  coarse  particles  which  are  in  Graham  flour,  and  which 
are  a  source  of  irritation  to  the  mucous  coat  of  the  digestive 
tube  in  some  persons.  (See  Appendix.) 

Water.  —  Water  constitutes  about  two-thirds  of  the  entire 
weight  of  the  body.  It  constitutes  the  bulk  of  the  liquids 
we  have  studied,  blood,  lymph,  sweat,  urine,  etc.  Water  is 
the  solvent  and  carrier  of  all  the  material  of  the  bod}'. 
Hence  we  need  a  large  amount  of  it;  of  course  we  must 
remember  that  we  get  a  good  deal  of  water  in  most  of  our 
solid  foods. 

Water,  as  it  comes  from  the  clouds,  is  pure.  After  enough 
rain  has  fallen  to  wash  the  air,  rain-water  is  pure,  and  if  caught 
on  a  clean  roof  (especially  a  slate  roof),  and  kept  in  a  clean 


WATER  IN   THE  BODY.  171 

cistern,  it  makes  good  drinking-water.  Falling  upon  the 
earth  the  rain-water  soaks  down  until  stopped  by  some  im- 
pervious layer,  such  as  clay.  This  water  is  the  supply  of  our 
wells  and  springs.  It  always  has  more  or  less  earthy  matter 
in  solution,  and  is  therefore  called  more  or  less  "  hard."  Un- 
less a  good  deal  of  mineral  matter  or  some  special  material  is 
dissolved  in  it,  it  is  ordinarily  good  drinking-water.  Such 
water  is  not  pure,  in  the  strict  sense  of  the  word,  but  is  pure 
for  drinking  purposes. 

The  great  source  of  danger  is  from  what  are  called  "  or- 
ganic "  impurities.  Most  bacteria  will  not  live  and  grow  in 
pure  water.  They  must  have  something  on  which  to  feed 
and  grow.  But  in  water  containing  a  good  deal  of  decaying 
animal  or  vegetable  matter  they  are  likely  to  abound.  And 
the  most  dangerous  sources  of  contamination  are  cesspools  and 
sewers.  Water  may  be  contaminated  by  such  material  and 
not  have  bacteria  in  it,  but  is  very  likely  to  harbor  such  foes. 
The  ordinary  cesspool  is  a  grave  source  of  danger.  Because 
a  well  may  be  on  higher  ground  than  the  cesspool  does  not 
give  assurance  that  the  water  may  not  be  polluted.  Often 
when  the  surface  of  the  ground  slopes  in  one  direction,  the 
strata  underneath  may  slope  in  just  the  opposite  direction, 
and  the  well  may  be  the  reservoir  into  which  the  cesspool  is 
drained. 

Good  authorities  say  that  a  cesspool  should  not  be  allowed 
within  a  hundred  feet  of  a  well. 

But  it  is  better  and  safer  to  have  no  cesspool.  Where  a 
sewer  system  is  not  to  be  had,  it  is  better  to  allow  no  great 
accumulation  of  such  material.  A  deep  pit  in  which  a  quan- 
tity of  semi-liquid  matter  gathers  is  not  only  a  nuisance,  but  a 
source  of  danger.  Privies  should  have  a  very  shallow  pit,  or 
none,  and  should  be  cleaned  often,  and  the  contents  disin- 
fected before  they  are  scattered  abroad  to  endanger  the  lives 


172  CONTAMINATION   OF   WATER. 

of  others.  There  should  be  a  little  dust  sprinkled  in  each  day, 
and  occasionally  some  "  chlorid  of  lime,"  or  sulfate  of  iron. 

Typhoid  fever  is  now  known  to  be  usually  caused  by 
drinking-water.  The  dejecta  of  some  one  who  has  had  the 
disease  find  their  way  into  the  source  of  the  drinking-water. 
In  many  cases  this  has  been  clearly  proved.  Of  course  the 
dejecta  of  all  such  patients  should  be  either  destroyed  or 
thoroughly  disinfected. 

Although  bacteria  will  not  develop  in  a  cold  place,  they 
are  not  killed  in  the  water  when  it  turns  to  ice,  as  was  for- 
merly supposed.  Further,  ice,  in  forming,  does  not  throw  out 
all  the  impurities,  as  was  formerly  stated.  So  it  is  not  safe 
to  drink  water  formed  from  melted  ice  unless  the  water  of 
which  that  ice  was  made  was  good  water.  The  ice  taken 
from  ponds  is  not  safe.  If  ice  is  made  artificially  from  suit- 
able drinking-water,  of  course  the  melted  product  will  be 
essentially  unchanged  so  far  as  the  composition  is  concerned. 
Water  may  be  cooled  by  placing  any  ice  around  it,  and  we 
may  have  the  desired  temperature  without  any  admixture  of 
a  dangerous  element. 

When  one  cannot  get  good  drinking-water,  or  when  away 
from  home  where  the  water  is  of  doubtful  purity,  it  is  better 
to  boil  the  water  before  using  it,  either  as  a  drink  or  in  pre- 
parations of  food  that  are  not  to  be  thoroughly  cooked.  It 
seems  to  be  proved  that  it  is  better  to  heat  the  water  twice  to 
near  the  boiling-point  than  to  boil  hard  once  only.  The  first 
heating  may  start  the  resistant  germs  into  more  active  life, 
causing  them  to  sprout  (so  to  speak),  and  a  second  heating 
several  hours  later  may  easily  kill  them ;  whereas  it  has  been 
proved  that  one  hard  boiling  will  not  always  kill  the  germs. 

Water  which  has  been  boiled  becomes  a  better  medium 
than  it  was  before  for  the  growth  of  bacteria  which  may  after- 
ward get  into  it,  or  whose  spores  may  have  escaped  death  in 


MIXED  DIET.  173 

the  boiling.  Therefore  only  enough  for  one  day's  use  should 
be  boiled  at  one  time-.  This  should  be  placed  in  a  clean  cov- 
ered vessel,  and  set  in  the  ice-chest  while  still  warm. 

Milk  which  is  to  be  fed  to  infants  and  children  should  be 
heated  till  it  steams,  thus  avoiding  danger  from  tubercle  bacilli. 

Or  if  one  uses  tea  and  coffee,  it  is  safer  to  content  one's 
self  with  these,  and  not  drink  much  water  till  that  which  is 
safe,  as  from  deep  wells,  can  be  obtained. 

In  hot  weather,  and  especially  for  those  who  are  engaged 
in  hard  work,  it  has  been  found  that  a  little  oatmeal  stirred 
in  the  water  is  beneficial.  Do  not  drink  ice-water. 

When  overheated  avoid  drinking  much  cold  water.  Ke- 
peatedly  rinse  the  mouth  with  cool  water,  and  swallow  very 
little.  This  is  the  way  trainers  manage  a  horse  at  a  race,  and 
it  is  sensible  to  treat  man  as  carefully. 

Salts.  —  Salts  include  many  substances  besides  common 
salt.  They  aid  in  the  solution  of  various  substances  during 
digestion  arid  in  other  processes.  We  cannot  live  without  salt. 

Lime  in  the  form  of  calcium  phosphate  and  calcium  car- 
bonate is  essential,  especially  in  the  bones  and  teeth.  Iron  is 
associated  with  hemoglobin. 

Necessity  of  a  Mixed  Diet.  —  Our  experience,  together 
with  the  results  of  the  experiments  on  animals,  teaches  that 
we  could  not  live  long  if  fed  on  any  one  class  of  foodstuffs 
alone.  We  must  take  a  representative  6f  each  of  the  groups. 
"\Ve  have  noticed  that  most  of  our  foods  already  contain  more 
than  one  foodstuff.  We  so  combine  them  as  to  get  suitable 
proportions.  Thus  we  eat  bread  and  butter  (a  small  amount 
of  fat  with  a  large  quantity  of  starch  and  a  little  gluten),  meat 
and  potato,  crackers  and  cheese,  pork  and  beans,  egg  on  toast, 
bread  and  milk,  rice  and  fowl,  macaroni  and  cheese ;  they  "  go 
well  together,"  chiefly  because  they  are  complementary. 

In  order  to  get  enough  nitrogen   from  bread  alone,  one 


174  MIXED  DIET. 

would  have  to  eat  about  four  pounds. a  day  ;  meanwhile  twice 
as  much  carbon  as  is  needed  would  be  taken,  thus  throwing 
an  undue  amount  of  work  upon  the  digestive  organs.  Again, 
one  would  need  to  consume  about  six  pounds  of  meat  to  get 
the  requisite  amount  of  carbon,  and  six  times  as  much  nitro- 
gen as  is  needed  would  be  taken ;  to  get  rid  of  this  extra 
nitrogen  would  severely  tax  the  kidneys  and  liver. 

In  cold  climates  a  large  amount  of  fat  is  consumed,  while 
in  the  tropics  starch  is  the  chief  food.  Our  appetites  call  for 
more  of  the  fatty  foods  during  the  winter  season. 

While  common  experience  has  led  people  to  adopt  a  mixed 
diet,  the  proportions  of  the  different  foodstuffs  is  not  always 
what  it  should  be.  The  proportions  of  the  foodstuffs  (exclu- 
sive of  water)  may  be  roughly  stated  as  about  1  part  of  pro- 
teid,  1  part  of  fat,  3  parts  of  carbohydrates.  But  this  will 
vary  somewhat  with  the  amount  of  work  done,  and  other 
varying  conditions.  (See  Tables  of  Dietaries  in  Appendix.) 

The  so-called  "  vegetarians  "  recognize  the  need  of  proteid 
food  ;  and  most  of  them  seek  proteid  in  eggs,  milk,  and  cheese. 
But  these  are  animal  products,  and  the  name  "  vegetarian  "  is 
inconsistent.  They  are  merely  "anti-meat  eaters."  If  they 
do  actually  succeed  in  getting  enough  proteids  from  the  le- 
gumes and  the  grains,  the  complete  digestion  of  which  is  diffi- 
cult, they  are,  as  Professor  Martin  says,  to  be  congratulated 
on  having  digestive  powers  that  can  stand  such  a  strain. 
That  we  are  adapted  for  using  flesh  as  part  of  our  food  is 
indicated  in  at  least  two  anatomical  features :  (1)  we  have 
canine  teeth,  though  not  so  fully  developed  as  in  the  carniv- 
ora ;  (2)  the  intestine  in  carnivora  is  very  short,  that  of  the 
herbivora  very  long,  but  in  man  intermediate. 

Tea  owes  its  stimulating  effects  to  a  substance  called 
Thein.  This  is  a  stimulant  to  the  nervous  system,  and  if  not 
too  strong  is  not  followed  by  a  subsequent  depression.  Tea 


TEA   AND   COFFEE.  175 

that  is  too  strong  is  likely  to  produce  nervousness  and  dys- 
pepsia. Boiling  the  tea-leaves  also  brings  out  the  tannic  acid 
that  they  contain,  and  produces  bad  effects. 

Coffee  owes  its  stimulating  effect  to  a  substance  called 
Caffein,  which  is  considered  identical  with  thein.  Coffee  acts 
as  a  restorative  after  hard  labor,  seeming  to  retard  the  wastes 
of  the  tissues  and  food.  It  is  used  in  the  army  (also  in  peni- 
tentiaries), not  as  a  luxury,  but  as  a  matter  of  economy  in 
the  matter  of  food  supply.  Coffee,  used  to  excess,  frequently 
causes  palpitation  of  the  heart. 

Malted  and  peptonized  milk  makes  a  valuable  drink  for  in- 
valids and  dyspeptics. 

Cocoa  contains  a  stimulant  called  Theobromin.  But  unlike 
tea  and  coffee,  cocoa  and  the  preparation  from  cocoa  known 
as  chocolate  are  true  foods,  by  virtue  of  the  fat  contained. 

Beef  tea  and  various  beef  extracts  are  very  beneficial. 
There  is  not  enough  nourishment  in  them  to  maintain  strength 
without  other  food.  Their  nutritive  value  has  been  somewhat 
over-estimated.  Their  value  is  as  much,  if  not  more,  in  their 
stimulating  as  in  their  nourishing  effect.  But  many  of  the 
soups  and  drinks  made  from  these  preparations  are  very  bene- 
ficial. They  refresh  the  tired  system  wonderfully.  Many  a 
man  who  takes  a  drink  of  liquor  to  "  brace  him  up,"  as  he 
says,  would  do  far  better  to  take  a  cup  of  hot  bouillon.  He 
would  find  himself  braced  up  for  the  time,  without  any  bad 
reaction,  or  permanent  injury  to  the  system. 

Alcohol.  —  Alcohol  is  not  a  food.  But  because  it  is  taken 
into  the  digestive  tube,  and  produces  its  effects  primarily 
through  the  digestive  system,  it  is  here  presented. 

If  we  eat  a  sufficient  amount  of  bread  to-day,  we  do  not 
crave  a  larger  amount  to-morrow  ;  but  the  appetite  for  alco- 
hol grows ;  the  law  of  its  use  is  the  law  of  increase,  until  the 
terrible  alcohol  habit  is  formed. 


176  EFFECTS   OF  ALCOHOL. 

Aside  from  the  fearful  effects  of  the  habitual  use  of  alco- 
hol upon  the  individual  himself,  statistics  show  that  a  large 
share  of  the  poverty  and  crime  in  the  world  is  due  to  its  use. 
Nearly  every  child  has  known  of  the  effects  in  the  family  of 
some  drunkard,  how  the  father  is  feared,  how  all  are  ashamed 
of  him,  how  the  children  are  poorly  clothed,  often  not  sent  to 
school,  because  not  sufficiently  supplied  with  clothes  and 
books ;  all  these,  and  the  dirt  and  misery  so  well  known  in 
so  many  cases,  are  a  sufficient  warning  not  to  make  the  slight- 
est beginning  of  this  habit.  History  is  full  of  accounts  of 
men  who  thought  they  could  stop  when  they  chose ;  the  grip 
of  the  alcohol  habit  is  almost  as  'relentless  as  the  grip  of 
death.  There  is  one  safe  rule.  "  Touch  not,  taste  not,  handle 
not." 

Some  of  the  best  authorities  state  that  alcohol,  taken  in 
small  doses,  is  oxidized  in  the  body,  producing  energy ;  but 
they  do  not  class  it  with  foods,  nor  do  they  recommend  its 
use. 

As  to  its  power  to  produce  heat,  the  fact  is  that,  as  ordi- 
narily taken,  alcohol  lowers  the  temperature  of  the  body.  It 
is  well  known  that  the  face  is  flushed  as  the  result  of  taking 
alcoholic  drink.  This  means  that  more  blood  has  been  sent 
to  the  skin.  This  sending  of  blood  to  the  skin  gives  a  sensa- 
tion of  heat ;  we  feel  hot  when  the  skin  is  flushed  from  other 
cause,  as  some  emotion.  But  if  the  temperature  of  the  body 
be  taken  at  the  time  when  the  body  feels  warm,  in  each  case 
it  may  be  found  that  the  temperature  is  actually  lowered; 
and  we  can  see  the  reason  for  this,  for  the  more  blood  there 
is  in  the  skin  the  more  heat  will  be  given  off,  and  thus  the 
amount  of  heat  in  the  body  diminished. 

Neither  does  alcohol  as  usually  taken  increase  the  energy 
of  the  body  so  far  as  muscular  work  is  concerned.  Experi- 
ence shows  that  men  can  endure  more  cold  and  more  hard 


EFFECTS   OF  ALCOHOL.  177 

labor  without  alcohol  than  with  it.  This  has  been  repeatedly 
proved  in  arctic  expeditions,  in  the  army  and  navy,  during 
the  hardships  and  exposures  of  forced  marches  and  depriva- 
tions in  all  climates. 

Especially  if  one  is  to  be  exposed  to  severe  cold  is  it  dan- 
gerous to  take  alcoholic  drink ;  many  a  member  of  exploring 
parties  has  lost  his  life  by  disobeying  this  rule. 

It  is  a  significant  fact  that  men  training  for  athletic  con- 
tests (no  matter  what  their  ordinary  habits  or  principles)  let 
alcoholic  drinks  alone.  One  of  the  famous  pugilists  said, 
"  I'm  no  teetotaler,  but  when  I  have  business  on  hand  there's 
nothing  like  water  and  dumbbells." 

"  Alcohol  is  a  typical  stimulant  j  it  acts  as  a  whip,  causing 
a  temporary  acceleration  of  physiological  activity.  Such  ac- 
celeration must  subsequently  be  paid  for,  the  extra  expendi- 
ture brought  about  by  alcohol  entailing  diminished  capacity 
for  further  exertion.  Alcohol  is  thus  of  service  only  for  emer- 
gencies of  short  duration  ;  it  is  eminently  harmful  when  pro- 
longed exertion  and  endurance  are  required.  Like  all  rapid 
stimulants,  alcohol  is  in  large  doses  a  direct  depressant."  — 
WALLER. 

Many  prefer  to  call  alcohol  a  narcotic.  In  large  doses  it 
seems  to  paralyze  the  mechanism  regulating  the  caliber  of 
the  arteries  ;  hence  the  flushing  above  noted.  Now,  when  the 
arteries  are  relaxed,  the  heart  works  harder  to  fill  the  greater 
space  offered,  and  is  thus  overworked. 

Alcohol  has  a  strong  affinity  for  water,  and  extracts  it  from 
tissues.  When  w,e  preserve  animal  tissue  in  alcohol,  the  al- 
cohol abstracts  the  water,  thus  hardening  and  preserving  the 
substance. 

Alcohol  should  be  classed  with  the  poisonous  drugs  (e.g., 
arsenic,  chloroform,  belladonna,  strychnin,  etc.),  the  exact  na- 
ture of  whose  effects  it  is  exceedingly  difficult  to  determine. 


178  EFFECTS   OF  ALCOHOL. 

We  do  know  that  they  are  very  dangerous  substances ;  and 
there  is  one  rule  that  will  apply  to  them  all :  Never  use  them 
except  under  the  advice  of  a  physician. 

"  The  most  serious  and  widespread  derangement  of  the 
natural  taste  is  that  caused  by  alcoholic  drinks.  Alcohol  has 
been  demonstrated  to  be  a  poison.  Its  continued  use,  even  in 
what  is  called  moderate  quantities,  will  pave  the  way  for 
many  diseases,  some  of  which  are  sure  to  overtake  those  who 
have  the  habit  of  using  drinks  with  alcohol  in  them. 

"  Examples  of  the  effect  of  the  excessive  use  of  alcoholic 
drinks  are  numerous  and  revolting  enough  in  most  communi- 
ties to  make  the  strongest  appeals  against  their  use. 

"  When  it  is  seen  that  by  the  use  of  alcohol  an  intelligent 
man  may  act  without  reason  ;  that  a  kind-hearted  man  may 
become  brutal  to  his  most  loved  friends ;  that  it  may  cause  an 
honorable  man  to  become  a  dishonorable  one  ;  that  it  may 
make  a  noble  nature  become  one  with  the  most  depraved  of 
tastes ;  when  its  use  has  over  and  over  again  been  the  cause  of 
disappointment,  of  intense  suffering,  and  of  crime,  —  it  would 
seem  that  vastly  stronger  reasons  existed  against  its  use  than 
the  mere  fact  that  some  slight  changes  in  the  tissues  occur 
which  might  possibly  be  demonstrated.  It  is  to  avoid  these 
serious  results  that  the  use  of  alcohol  is  to  be  shunned,  and 
not  simply  to  avoid  a  differently  shaped  liver. 

"  The  physiological  effects  of  poisons  are  generally  much 
greater  than  the  visible  changes  which  they  produce  in  the 
tissues  would  lead  us  to  expect.  Indeed,  such  effects  can  sel- 
dom be  detected  by  changes  seen  in  the  tissue  cells. 

"  Strychnin  produces  powerful  spasms  which  end  in  death. 
It  acts,  it  is  said,  on  the  spinal  cord,  but  it  would  be  hard  to 
show  any  changes  that  it  produces  in  the  cells.  And  a  knowl- 
edge of  the  changes  it  produces  in  the  cells  could  not  make 
us  fear  the  poison  any  more  than  we  do,  who  know  that  it 
results  in  suffering  and  death."  —  JENKINS. 


EFFECTS    OF  ALCOHOL.  179 

Many  well-meaning  persons  use  the  various  preparations 
called  "  root  beers,"  perhaps  without  realizing  that  most,  if 
not  all,  contain  yeast,  and  in  their  preparation  undergo  fer- 
mentation, producing  alcohol,  though  not  ordinarily  in  large 
amounts.  By  giving  such  drinks  (often  called  "  temperance 
drinks  ")  to  children,  an  appetite  for  alcohol  may  be  cultivated 
and  the  beginning  of  a  terrible  habit  made.  (And  it  may  be 
well  here  to  note  the  real  meaning  of  the  word  habit,  that 
which  holds  us.) 

Nor  is  it  advisable  to  keep  cider  about  a  house  where  there 
are  children.  "  It  is  perfectly  sweet,"  you  say.  Yes,  but 
unless  it  is  all  soon  consumed  it  will  ferment.  It  is  unwise, 
to  say  the  least,  to  put  temptation  in  the  way  of  those  whose 
habits  are  not  formed. 

ALCOHOL   IN   THE   BODY. 

[GRAHAM  LUSK,  Ph.D.,  Professor  of  Physiology  in  the  Yale  Medical  School,  from 
the  chapter  on  "The  Chemistry  of  the  Animal  Body,"  in  HowelPs  American 
Text-Book  of  Physiology.} 

"  Alcohol  in  the  stomach  at  first  prevents  the  gelatinization 
necessary  in  proteid  for  peptic  digestion  ;  but  this  difficulty  is 
of  no  great  moment,  because  the  absorption  of  alcohol  is  rapid 
and  complete.  It  makes  the  mucous  membrane  hyperemic, 
promotes  the  absorption  of  accompanying  substances  (sugar, 
peptone,  potassium  iodide),  and  stimulates  the  flow  of  gastric 
juice.  In  this  matter  it  acts  as  do  other  condiments  (salt, 
pepper,  mustard,  peppermint),  but  if  there  be  too  great  an 
irritation  of  the  mucous  membrane  there  is  less  activity  (dys- 
pepsia). The  rapid  absorption  gives  to  alcohol  its  quick  re- 
cuperative effect  after  collapse,  and  its  value  in  administering 
drugs,  especially  antidotes.  Alcoholic  beverages,  combining 
alcohol  and  flavor,  promote  gastric  digestion  and  absorption,  but 
often  stimulate  the  appetite  in  excess  of  normal  requirement. 


180  EFFECTS   OF  ALCOHOL. 

Alcohol  is  burned  in  the  body,  but  may  also  be  found  in  the 
breath,  perspiration,  urine,  and  milk.  Alcohol  has  no  effect 
on  proteid  decomposition,  but  acts  to  spare  fat  from  combus- 
tion. The  addition  of  50  to  80  grams  of  alcohol  to  the  food 
has  no  apparent  effect  on  the  nitrogenous  equilibrium.  Alco- 
hol in  the  body  acts  as  a  paralyzant  on  certain  portions  of  the 
brain,  destroying  the  more  delicate  degrees  of  attention,  judg- 
ment, and  reflective  thought,  diminishing  the  sense  of  weari- 
ness (use  after  great  exertion  furnished  to  armies  in  the  last 
hours  of  battle),  and  raising  the  self-esteem ;  it  paralyzes  the 
vasoconstrictor  nerves,  producing  turgescence  of  the  skin,  with 
accompanying  feeling  of  warmth,  and  thereby  indirectly  aiding 
the  heart." 

STIMULANTS. 

[WILLIAM  H.  HOWELL,  Ph.D.,  M.D.,  Professor  of  Physiology,  Johns  Hopkins 
University,  American  Text-Book  of  Physiology.] 

11  The  well-known  stimulating  effect  of  alcohol,  tea,  coffee, 
etc.,  is  probably  due  to  a  specific  action  on  the  nervous  sys- 
tem whereby  the  irritability  of  the  tissue  is  increased.  The 
physiological  effect  of  tea,  coffee,  and  chocolate  is  due  to  the  al- 
kaloid caffeine  (trimethyl  xanthin)  and  theobromine  (dimethyl 
xanthin).  In  small  doses  these  substances  are  oxidized  in  the 
body  and  yield  a  corresponding  amount  of  energy,  but  their 
value  from  this  standpoint  is  altogether  unimportant  compared 
with  their  action  as  stimulants.  Alcohol  also,  when  not  taken 
in  too  large  quantities,  may  be  oxidized  in  the  body,  and  fur- 
nish a  not  inconsiderable  amount  of  energy.  It  is,  however, 
a  matter  of  controversy  at  present  whether  alcohol  in  small 
doses  can  be  considered  a  true  foodstuff,  capable  of  serving 
as  a  direct  source  of  energy,  and  of  replacing  a  corresponding 
amount  of  fats  or  of  carbohydrates  in  the  daily  diet.  The 
evidence  is  partly  for  and  partly  against  such  a  use  of  alcohol. 


EFFECTS   OF  ALCOHOL.  181 

When  alcohol  is  taken  in  excess  it  produces  the  familiar 
symptoms  of  intoxication,  which  may  pass  subsequently  into 
a  condition  of  stupor  or  even  death,  provided  the  quantity 
taken  is  sufficiently  great.  So,  also,  the  long-continued  use  of 
alcohol  in  large  quantities  is  known  to  produce  serious  lesions 
of  the  stomach,  liver,  nerves,  blood-vessels,  and  other  organs. 
The  effect  of  alcohol  upon  the  body  evidently  varies  greatly 
with  the  quantity  used." 

EFFECT    OF    ALCOHOL    ON    MOUNTAIN    CLIMBERS. 

[From  The  Nation.] 

"  Dr.  Otto  Snell  issued  a  card  requesting  mountain  climb- 
ers to  forward  their  personal  experiences  and  views  to  him. 
He  received  sixty  communications,  thirty-seven  of  which,  or 
62%,  condemn  the  use  of  liquors,  wine,  or  beer,  as  an  impedi- 
ment rather  than  an  aid.  Twelve  are  for  a  moderate  use  of 
wine,  but  pronounce  against  brandy  and  beer.  Three  believe 
in  taking  brandy  along,  to  be  used,  however,  not  as  a  stimu- 
lant, but  in  case  of  need  as  a  medicine  or  to  mix  with  gla- 
cier water.  Only  five  of  the  sixty  expressed  their  belief  that 
alcoholic  drinks  are  beneficial  or  harmless  to  climbers.  The 
general  conclusion  drawn  by  Dr.  Snell  from  these  answers  is 
that,  while  in  exceptional  cases  alcohol  may  be  harmless,  or 
possibly  useful,  as  a  rule  great  moderation  is  desirable ;  while 
the  majority  of  experts  are  for  total  abstinence  until  after 
the  climb  is  over,  and  some  even  strongly  urge  abstinence,  or 
great  moderation,  on  the  day  before  the  expedition.  One  of 
the  correspondents  expressed  his  conviction  that  the  bottled 
drinks  taken  along  by  climbers  benefit  no  one  but  the  tavern- 
keepers  from  whom  they  buy  them." 

In  August,  1897,  the  writer  climbed  Pike's  Peak,  and  spent 
the  night  there.  The  keeper  of  the  house  there  testified  that 
those  who  took  alcoholic  drink  for  the  relief  of  giddiness, 


182  EFFECTS   OF  ALCOHOL. 

nausea,  or  other  distress  that  often  is  felt  as  a  result  of  the 
effort  of  climbing  in  such  altitude,  —  that  almost  invariably 
such  symptoms  were  aggravated  instead  of  being  relieved. 
Dr.  Hodge,  in  an  article  in  Popular  Science  Monthly  (March 
and  April,  1897),  entitled  "Experiments  on  the  Physiology 
of  Alcohol,"  makes  the  following  quotations,  "  Hemholtz  has 
said,  in  describing  his  methods  of  work,  that  slight  indulgence 
in  alcoholic  drinks  dispelled  instantly  his  best  ideas.  Profes- 
sor Gaule  once  told  the  writer,  as  an  experiment  during  the 
strain  of  his  '  Staatsexamen,'  that  he  suddenly  stopped  his 
wine  and  beer,  and  was  surprised  to  find  how  much  better  he 
could  work.  An  eminent  professor  in  Leipsic  once  said  that 
the  German  students  could  do  '  twice  as  much  work 7  if  they 
would  let  their  beer  alone.  Dr.  August  Smith  has  found  that 
moderate  non-intoxicant  doses  of  alcohol  (forty  to  eighty  cubic 
centimeters  daily)  lowered  psychic  ability  to  memorize  as  much 
as  seventy  per  cent." 

[From  THOMPSON  's  Practical  Dietetics.'] 

"...  the  following  general  propositions  comprise  the 
belief  of  many  authorities  who  have  devoted  careful  research 
to  this  exceedingly  important  topic  :  — 

"  1.  The  use  of  alcohol  in  any  shape  is  wholly  unnecessary 
for  the  use  of  the  human  organism  in  health.  It  does  not 
exist  as  a  natural  product.  The  very  lowest  types  of  man  — 
Australian  and  many  Polynesian  savages  —  know  nothing  of 
it,  and  drink  only  water  and  fresh  fruit  juice,  such  as  that  of 
the  cocoanut,  although  they  speedily  acquire  a  fondness  for 
alcohol  when  it  is  given  them. 

"  2.  A  large  number  of  persons  are  undoubtedly  better  with- 
out alcohol,  and  may  prolong  their  lives  by  total  abstinence. 

"  3.  The  lifelong  use  of  alcohol  in  moderation,  as  an  occa- 
sional beverage  with  meals,  does  not  necessarily  shorten  the 
duration  of  life  or  induce  disease  in  some  persons,  while  in 


EFFECTS   OF  ALCOHOL.  183 

others  it  undoubtedly  produces  gradual  and  permanent  changes, 
chiefly  of  a  cirrhotic  character,  in  the  blood-vessels  and  viscera, 
such  as  the  liver  and  kidneys.  These  alterations,  which  may 
be  slow  and  subtile  in  character,  may  not  in  themselves  mate- 
rially impair  the  health  or  cause  an  ultimately  fatal  result ;  but 
they  tend  to  weaken  vital  organs  and  produce  a  condition  of 
premature  senility,  so  that  if  the  patient  be  overtaken  by  any 
severe  disease,  as,  for  example,  by  an  acute  infection  like 
pneumonia,  or  a  chronic  one  like  pulmonary  tuberculosis,  the 
resistance  of  the  body  to  the  force  of  the  disease  is  materially 
impaired,  and  the  danger  to  the  patient  is  seriously  enhanced. 

"  4.  There  are  many  persons  whose  constitutional  inherit- 
ance is  such  that  they  should  be  particularly  warned  against 
the  use  of  alcohol ;  and  in  some  such  cases,  as,  for  example, 
among  those  who  are  subjects  of  well-marked  gouty  diathesis, 
it  is  better  that  the  use  of  alcohol  should  be  imperatively  for- 
bidden. 

"  5.  The  abuse  of  alcoholic  stimulation  is  invariably  inju- 
rious, although  the  extent  to  which  evil  influences  become 
manifest  depends  upon  the  constitution  of  the  individual,  in 
connection  with  the  two  factors  of  heredity  and  environment. 

"  6.  There  are  a  number  of  diseases  in  which  the  temporary 
use  of  alcohol  is  of  positive  service,  and  there  are  a  number  of 
cases  in  which  it  becomes  a  necessity  in  order  to  prolong  life. 

'*  7.  In  many  cases  of  malnutrition  and  malassimilation  of 
food,  alcohol  is  itself  a  food ;  and  its  consumption  under  proper 
direction  results  in  an  increase  of  body  weight  and  strength, 
and  improvement  of  functional  activity.  These  results  are 
accomplished  in  part  through  the  action  of  the  alcohol  as  a 
definite  food,  and  in  part  through  its  remarkable  effect  in  force 
production.  The  latter  is  due  to  its  own  direct  combustion, 
by  which  in  chronic  diseases  and  in  critical,  acute,  and  exhaust- 
ing affections  it  spares  that  of  the  tissues  of  the  body. 


184  EFFECTS   OF  ALCOHOL. 

"  Although  alcohol  is  such  a  strong  force  producer  and  heat 
generator,  its  effect  in  this  direction  is  very  soon  counterbal- 
anced by  its  stronger  influence  in  lowering  the  general  tone  of 
the  nervous  system,  and  in  producing  positive  degeneration  in 
the  tissues.  In  the  condition  of  health  more  food  is  usually 
eaten  and  more  force  is  developed  than  are  actually  necessary 
for  the  body,  and  there  is  constantly  a  reserve  supply  of  energy 
on  hand  which  may  be  utilized  for  any  extraordinary  exertion  ; 
and  hence  the  constant  use  of  alcohol  as  a  food  or  stimulant 
in  health  is  both  unnecessary  and  unadvisable.  When  alcohol 
is  consumed  in  health  in  addition  to  a  normal  or  excessive 
quantity  of  solid  food,  by  its  more  ready  combustion  it  pre- 
vents the  complete  oxidation  of  the  latter,  and  favors  the  ac- 
cumulation of  suboxidized  waste  products,  which  are  always 
harmful  in  the  system.  Excesses  in  eating  are  thus  doubly 
aggravated  by  the  effects  of  alcohol.  It  is  the  almost  uni- 
versal testimony  of  army  surgeons,  and  the  experience  of  those 
who,  like  Greely,  Stanley,  and  others,  have  led  long  and  peri- 
lous exploring  expeditions  involving  great  fatigue  and  unusual 
endurance,  that  muscular  overwork  and  climatic  hardships  are 
much  better  endured  if  alcohol  is  entirely  abstained  from. 

"  It  has  always  been  found  in  armies,  that  when  good  food 
was  at  hand  the  issue  of  alcohol  with  the  regular  ration  pro- 
duced an  increased  percentage  of  sick  days  and  of  incapacity 
for  work.  Col.  A.  A.  Woodhull,  surgeon  U.  S.  army,  writes 
me :  '  I  do  not  think  that  any  of  our  medical  officers  would 
seriously  advocate  the  issue  of  alcohol  as  a  measure  of  health ; 
but  I  believe  that  its  habitual  use  during  the  Rebellion  was 
prohibited  for  reasons  of  discipline,  while  it  still  might  have 
been  occasionally  issued  as  if  for  health.  On  the  rare  occa- 
sions when  it  might  serve  a  good  purpose,  as  a  temporary  stim- 
ulant after  a  long  and  wet  march,  the  wagons  would  be  in  the 
rear,  owing  to  the  same  conditions  that  fatigued  the  men.' 


EFFECTS   OF  ALCOHOL.  185 

"  While  all  this  applies  to  prolonged  effort  of  any  kind, 
and  to  conditions  where  other  food  can  be  obtained  and  assimi- 
lated, it  does  not  detract  from  the  fact  that  alcohol  is  a  most 
helpful  food  and  stimulant  in  emergencies,  when  other  food 
cannot  be  had,  or  when  the  body  is  temporarily  endangered 
from  acute  disease  and  the  higher  rate  of  combustion  in  fever, 
or  from  failure  to  assimilate  other  nourishment. 

"  Captain  Woodruff,  assistant  surgeon  United  States  army, 
says,  '  Spirits  can  never  be  used  in  the  army  as  a  regular 
issue ;  the  practice  is  thoroughly  vicious,  and  was  virtually 
abandoned  sixty  years  ago.  On  extraordinary  occasions  of 
great  fatigue  they  are  allowable  in  moderation.  Under  such 
temporary  stimulation  the  men  will  brace  up  arid  perform  the 
necessary  work  of  making  earthworks,  etc.,  when  without  it 
they  would  be  too  exhausted  to  do  anything.  Without  such 
stimulation  a  man  is  not  worth  much  after  he  has  made  a 
forced  march  of  forty  miles.7 

"  The  problem  whether  the  world  as  a  whole  is  better  or 
worse  for  the  existence  of  alcohol,  aside  from  all  ethical  ques- 
tions, and  viewed  merely  from  the  scientific  standpoint  of  the 
influence  of  alcohol  upon  mortality,  is  difficult  of  solution ; 
for  to  offset  the  numerous  cases  of  fatal  alcoholism,  and  the 
still  larger  number  of  cases  of  diseases  which  would  not  pre- 
sumably be  fatal  without  the  existing  condition  of  chronic 
alcoholic  poisoning  of  the  system,  are  very  many  cases,  among 
both  infants  and  adults,  in  which  life  is  undoubtedly  saved  by 
the  prompt  resort  to  this  food  and  stimulant,  and  its  energetic 
use.  So  long  as  man  is  exposed  to  hardships  and  conditions 
arising  from  improper  and  deficient  food  supply,  as  well  as  to 
the  numerous  infectious  diseases  to  which  he  is  heir,  alcohol 
must  still  be  regarded  rather  as  a  blessing  than  a  curse  ;  for 
there  is  no  form  of  stimulant  and  food  combined,  or  stimulant 
alone,  which,  taken  all  in  all,  can  be  so  completely  relied  upon 


186  EFFECTS   OF  ALCOHOL. 

in  cases  of  emergency.     Alcohol  when  taken  alone  will  prolong 
life  beyond  the  period  at  which  it  terminates  from  starvation." 


BEVERAGES    CONTAINING    ALCOHOL. 
[ROHfe,  Text-Book  of  Hygiene.] 

"  The  physiological  action  of  alcohol  has  been  pretty  fully 
worked  out  by  Binz  and  his  pupils,  and  by  other  experiment- 
ers. From  these  researches  it  appears  that  the  first  effect 
of  taking  alcohol,  sufficiently  diluted,  into  the  stomach  is  to 
increase  the  flow  of  saliva  and  gastric  juice.  This  effect  is 
probably  reflex,  and  results  from  a  stimulation  of  nerve  ter- 
minations in  the  stomach.  The  alcohol  is  rapidly  absorbed, 
and  is  carried  in  the  blood,  without  undergoing  chemical 
change,  to  the  nervous  centers,  lungs,  and  tissues  generally. 
In  the  brain  the  alcohol  probably  enters  into  combination  with 
the  nervous  tissue,  modifying  the  normal  activity  of  the  vari- 
ous centers,  either  increasing  the  activity,  if  the  alcohol  is  in 
small  quantity  (stimulating  effect),  or  diminishing  it,  if  in 
larger  quantity  (depressing  effect),  or  entirely  suspending  the 
activity  of  the  centers,  if  in  sufficiently  large  quantity  (para- 
lyzing effect). 

"  Alcohol  stimulates  the  vasodilator  nerves,  causing  dilata- 
tion of  the  smaller  vessels ;  in  consequence  of  this  the  blood 
is  largely  sent  to  the  periphery  of  the  body,  the  blood-pressure 
diminishes,  and  heat  radiation  is  increased.  At  the  same  time 
a  portion  of  the  alcohol  is  used  up  in  the  production  of  animal 
heat,  thus  economizing  the  expenditure  of  fats  and  proteids, 
and  acting  as  a  true  respiratory  food.  Alcohol  does  not  con- 
tribute nutritive  material  to  the  body ;  it  only  permits  that 
which  is  stored  up  to  be  saved  for  other  uses,  by  furnishing 
easily  oxidizable  (combustible)  material  for  carrying  on  the 
respiratory  process  and  supplying  animal  heat. 


EFFECTS   OF  ALCOHOL.  187 

"  During  the  use  of  alcohol  the  excretion  of  urea  is  dimin- 
ished. This  shows  that  waste  of  tissue  is  retarded  in  the  body. 

"  Eegarding  the  statement  of  some  authorities  that  alcohol 
does  not  undergo  any  change  in  the  body,  but  is  excreted 
unchanged,  Binz  asserts  that  alcohol  appears  in  the  urine  only 
when  exceptionally  large  quantities  have  been  taken,  and  then 
in  very  small  proportion.  It  is  not  excreted  by  the  lungs,  the 
peculiar  odor  of  the  breath  being  due  not  to  the  alcohol,  but 
to  the  volatile  aromatic  ether,  which  is  oxidized  with  greater 
difficulty,  and  so  escapes  unchanged. 

"While  alcohol  produces  subjectively  an  agreeable  sen- 
sation of  warmth  in  the  stomach  and  on  the  surface  of  the 
body,  the  bodily  temperature  is  not  raised.  The  subjective 
sensation  is  due  to  the  dilatation  of  the  blood-vessels  and  the 
sudden  hypersemia  of  those  parts. 

"During  fevers  and  other  exhausting  diseases  alcohol  is 
invaluable  to  prevent  waste  of  tissue  and  sustain  the  strength. 
It  does  not  act  merely  as  a  stimulant  to  the  circulation  and 
nervous  system,  but,  as  above  pointed  out,  saves  the  more 
stable  compounds  by  furnishing  a  readily  oxidizable  respira- 
tory food. 

"When  taken  in  small  doses  by  healthy  persons  alcohol 
diminishes  the  temperature  by  increasing  heat  radiation. 
When  large  quantities  are  taken  the  bodily  temperature  is 
reduced  by  diminishing  heat  production,  as  well  as  by  increased 
radiation.  This  is  shown  in  the  condition  known  as  dead- 
drunkenness,  in  which  the  temperature  is  sometimes  depressed 
as  much  as  20°  F.  below  the  normal.  Cases  in  which  the 
temperature  sank  to  75°,  78.8°,  and  83°  F.  have  been  re- 
ported, with  recovery  in  all  cases. 

"  The  constant  use  of  alcohol  produces  in  all  the  organs  an 
excess  of  connective  tissue,  followed  by  fatty  degeneration  and 
the  condition  known  as  cirrhosis.  The  organs  most  frequently 


188  EFFECTS  OF  ALCOHOL. 

affected  are  the  stomach,  liver,  and  kidneys.  Serious  patho- 
logical alterations  also  occur  in  the  circulatory,  respiratory, 
and  nervous  systems. 

"  Alcohol  is  not  necessary  to  persons  in  good  health.  Prob- 
ably most  persons,  regardless  of  their  state  of  health,  do  better 
without  it.  Its  habitual  use,  in  the  form  of  strong  liquors,  is 
to  be  unreservedly  condemned.  The  lighter  wines  and  malt 
liquors,  if  obtained  pure,  may  be  consumed  in  moderate  quan- 
tities without  ill  effects.  Even  in  these  forms,  however,  the 
use  of  alcohol  should  be  discouraged,  or  perhaps  prohibited,  in 
the  young. 

"Neither  in -hot  nor  in  cold  climates  is  alcohol  necessary 
to  the  preservation  of  health,  and  its  moderate  use  even  pro- 
duces more  injury  than  benefit.  The  polar  voyager  and  the 
East  India  merchant  are  alike  better  off  without  alcohol  than 
with  it. 

"  It  has  long  been  a  prevalent  belief  that  the  use  of  alco- 
hol enables  persons  to  withstand  fatigue  better  than  where  no 
alcohol  is  used.  A  large  amount  of  concurrent  testimony 
absolutely  negatives  this  belief. 

"  The  predisposition  to  many  diseases  is  greatly  increased 
by  the  habitual  use  of  alcohol.  Sunstroke,  the  acute  infec- 
tious diseases,  and  many  local  organic  affections,  attack,  by 
preference,  the  intemperate.  A  recent  collective  investigation 
by  the  British  Medical  Association  brought  out  the  fact  that 
croupous  pneumonia  is  vastly  more  fatal  among  the  intemper- 
ate than  among  those  who  abstained  from  the  use  of  alcoholic 
liquors. 

"A  further  investigation  by  Baer  has  shown  that  the 
average  expectation  of  life  among  users  and  dealers  in  alco- 
holic liquors  is  very  much  shortened.  The  following  table 
gives  a  comparative  view  of  the  expectation  of  life  in  those 
who  abstained  from  and  those  who  used  alcohol :  — 


EFFECTS   OF  ALCOHOL.  189 


EXPECTATION  OF  LIFE. 

AGE.  ABSTAINERS.  ALCOHOL   USERS. 

At  25,  32.08  years.  26.23  years. 

"  35,  25.92      "  20.01      " 

"  45,  19.92      "  15.19      " 

"  55,  14.45      "  11.16      " 

"  65,                      9.62      "  8.04      " 


TABLE  SHOWING  THE  INFLUENCE  OF  ALCOHOL   UPON  THE 
MORTALITY  FROM   VARIOUS   DISEASES. 

GENERAL  MALE  POPULATION.   ALCOHOL  VENDERS. 

Brain  disease,  11.77  per  cent.  14.43  per  cent. 

Tuberculosis,  30.36  "  36.57 

Pneumonia  and  pleuritis,         9.63  "  11.44  " 

Heart  disease,  1.46  "  3.29  " 

Kidney  disease,  1.40  "  2.11  " 

Suicide,  2.99  ««  4.02  " 

Cancer,  -   .        2.49  "  3.70  " 

Old  age,  22.49  "  7.05  " 


ACCESSORIES    TO    FOOD. 

[HALLIBURTON,  Text-Book  of  Chemical  Physiology  and  Pathology.] 

"  Alcohol.  —  Small  quantities  of  the  alcohol  taken  leave 
the  body  by  the  breath  and  urine  as  such,  the  greater  amount 
is  decomposed  into  simpler  products  (acetic,  oxalic,  carbonic 
acids,  and  water)  ;  the  formation  of  these  must  give  rise  to  a 
certain  amount  of  bodily  heat.  It  has  been  calculated  that  a 
man  can  burn  off  in  his  body  two  ounces  of  absolute  alcohol 
daily.  Alcohol  is  thus,  within  narrow  limits,  a  food.  It,  how- 
ever, lessens  proteid  metabolism  by  about  6  per  cent,  and  thus 
ultimately  leads  to  a  diminution  of  the  heat  produced  in  the 
body.  It  is,  moreover,  a  very  uneconomical  food  ;  much  more 
nutriment  would  have  been  obtainable  from  the  barley  or  the 
grapes  from  which  it  was  made.  The  value  of  alcohol  used 


190  EFFECTS   OF  ALCOHOL. 

within  moderate  limits  is  not  as  a  food,  but  as  a  stimulant  not 
only  to  digestion,  but  to  the  heart  and  brain.'' 

[M'KENDBICK,  Text-Book  of  Physiology.} 

"  With  regard  to  alcohol,  its  exact  influence,  when  taken  in 
moderation  by  those  who  use  it  as  an  article  of  diet,  cannot  be 
precisely  stated.  It  has  been  asserted  by  several  observers 
that  alcohol  is  eliminated  from  the  body  as  alcohol  by  the 
various  excretory  channels.  The  evidence  of  this  is  doubtful, 
and  it  is  probable  that  it  is  split  up  into  simpler  compounds. 
...  A  small  part  of  the  alcohol  ingested  no  doubt  is  exhaled 
by  the  mucous  membrane  of  the  lungs  and  by  the  kidneys. 
The  odor  of  the  breath  depends  on  the  elimination  of  oxida- 
tion products,  such  as  fusel  oil.  If  oxidized  even  to  a  small 
extent,  and  the  evidence,  as  already  indicated,  points  to  the 
oxidation  of  by  far  the  larger  proportion  of  it  (95  per  cent), 
alcohol  must  be  regarded,  in  the  scientific  sense,  as  a  food.  No 
doubt  also  its  ingestion  diminishes  the  metabolism  of  proteids 
to  the  extent  of  about  6  per  cent,  as  shown  by  the  diminished 
excretion  of  urea.  Its  oxidation  will  also  be  attended  by  the 
production  of  heat ;  but  as,  on  the  other  hand,  it  lessens  the 
production  of  heat  by  interfering  with  the  metabolism  in  pro- 
teid  tissues,  and  also  by  diminishing  the  oxidation  of  carbo- 
hydrates and  fats,  the  final  result  is  an  actual  diminution  of 
bodily  temperature.  While,  therefore,  alcohol  must  be  classed 
technically  as  a  food,  it  is  in  many  respects  an  unsuitable  food, 
and  its  place  can  be  taken  with  great  advantage  by  other 
substances.  In  small  doses  it  acts  as  a  local  excitant  of  the 
digestive  mucous  membrane,  and  afterwards  as  a  diffusible 
stimulant  upon  the  circulation  and  central  nervous  system. 
In  some  cases  it  may  aid  the  digestive  process ;  but  in  a  state 
of  health  it  is  not  only  not  required,  but  its  use,  except  in 
small  doses,  is  positively  prejudicial." 


EFFECTS   OF  ALCOHOL.  191 

These  various  authorities  have  thus  been  freely  quoted,  to 
show  that  while  there  is  considerable  divergence  of  opinion  in 
regard  to  some  of  the  physiological  effects  of  alcohol,  they  are 
substantially  agreed  as  to  the  following  points  :  — 

1.  Alcohol  is  not  needed  in  health. 

2.  While  technically  it  may  be  called  a  food,  practically  it 
is  a,  poison,  and  its  use  is  dangerous. 

The  danger  is  especially  great  where  there  is  a  latent  he- 
reditary tendency  to  inebriety  or  insanity.  The  danger  is  also 
very  great  when  the  disease  for  which  alcohol  is  prescribed 
is  accompanied  by  melancholy  and  depression.  Many  indi- 
viduals, on  finding  a  drug  which  exhilarates  and  banishes  the 
weight  of  oppression  by  which  they  are  borne  down,  are 
tempted  beyond  their  power  of  resistance,  even  though  the 
reaction  brings  them  into  a  worse  condition  than  the  one  from 
which  they  sought  relief. 

The  pressure  of  modern  life,  and  the  intensity  of  the  strug- 
gle for  a  living,  brings  about  a  condition  of  nervous  strain  that 
is  fraught  with  great  danger.  Every  thinking  man  should 
see  that  to  use  alcoholic  drink  for  the  relief  of  such  a  condi- 
tion is  like  venturing  out  in  a  boat  above  the  Falls  of  Niagara, 
—  he  knows  not  when  the  rushing,  mighty  power  will  gain  the 
mastery  and  dash  him  to  destruction. 

Tobacco.  —  The  use  of  tobacco  is  needless.  Man  gets  along 
well  enough  without  it.  It  is  injurious  to  many.  It  is  an  ex- 
pensive habit.  Many  a  man  spends  enough  on  tobacco  to  send 
a  boy  through  college.  With  the  excellent  cheap  printing  of 
to-day,  many  of  the  very  best  books  may  be  bought  for  the 
money  that  is  paid  for  as  many  cigars.  Even  for  those  who 
can  abundantly  afford  it,  it  seems  extremely  selfish,  when  it  is 
needless,  and  there  is  so  much  good  that  might  be  done  with 
the  money.  Another  very  selfish  feature  is,  that  so  many  men 
do  not  seem  to  consider  the  fact  that  the  air  is  public  prop- 


192  TOBACCO. 

erty,  and  they  have  no  right  to  fill  the  air  with  any  gas  or 
smoke  that  is  offensive  to  others.  Very  likely  many  men  de- 
rive great  comfort  from  the  use  of  tobacco  after  they  have 
once  formed  the  habit ;  but  most  of  these  were  made  sick  in 
learning,  showing  that  the  use  is  unnatural. 

It  seems  to  be  clearly  proved  that  cigarette  smoking  is 
very  injurious,  especially  to  boys.  And  if  men  smoke  cigars, 
the  example  is  set  for  the  boys  to  smoke  cigarettes.  Many  of 
the  cigarettes  are  said  to  be  steeped  in  preparations  of  opium  ; 
so  that  the  use  of  cigarettes  is  often  subjecting  the  user,  not 
only  to  the  tryanny  of  tobacco,  but  to  that  of  opium  as  well. 

Perhaps  Robinson  Crusoe  might  have  been  excused  for 
using  tobacco,  having  no  one  to  save  money  for,  no  unfortu- 
nates to  aid,  no  children  to  educate,  no  one  to  whom  he  might 
set  a  bad  example,  no  one  whose  breath  of  air  he  could  contam- 
inate, no  one  to  smell  his  breath,  no  one  to  see  the  offensive 
results.  But  a  man  living  in  the  society  of  so  many  to  whom 
this  habit,  in  all  its  features,  is  so  disgusting  and  in  every 
way  offensive,  ought  seriously  to  consider  whether  he  is  doing 
right  in  continuing  such  a  practice. 

Many  boys  seem  to  think  it  is  manly  ;  they  wish  to  do  as 
others  do.  It  is  not  manly  to  imitate  any  one.  Do  nothing 
simply  because  some  one  else  does  it.  To  do  this  is  to  be  a 
slave,  to  be  led.  And  one  bad  feature  of  the  tobacco  habit  is 
that  one  makes  himself  a  slave  to  the  weed.  For,  like  other 
narcotics,  it  has  a  powerful  influence  on  the  system ;  and  the 
habit,  once  formed,  is  hard  to  break. 

How  many  men  have  been  heard  to  say,  "  I  wish  I  had 
never  formed  the  habit." 

Has  any  one  in  middle  or  later  life  ever  been  heard  to  say, 
"  I  wish  I  had  formed  this  habit "  ? 

Cooking.  —  Cooking  is  designed  to  make  food  more  pala- 
table and  more  digestible.  Some  foods,  such  as  eggs,  are  as 


COOKING.  193 

digestible  before  they  are  cooked  as  after,  often  more  so,  as 
they  are  very  frequently  badly  cooked.  But  many  foods  in 
the  raw  state  are  unattractive,  or  even  repellent,  whereas 
cooking  usually  develops  an  agreeable  odor  and  taste.  Cook- 
ing should  soften  the  harder  and  tougher  tissues,  such  as  cel- 
lulose in  vegetables  and  the  connective  tissue  of  animal  foods. 

If  meat  be  put  into  cold  water  and  the  water  gradually 
warmed,  the  soluble  material  of  the  meat  may  be  extracted ; 
and  this  is  the  principle  followed  in  making  soups.  But  if 
we  wish  to  cook  the  meat  itself,  the  juices  should  be  retained 
instead  of  withdrawn.  For  this  purpose  boiling  water  is 
poured  over  the  meat  to  coagulate  the  outer  layer,  and  pre- 
vent the  extraction  of  the  juices.  The  same  principle  applies 
to  baking  and  roasting  and  also  to  broiling.  The  outside  is 
subjected  to  high  heat  at  the  beginning  of  the  cooking,  which 
forms  a  layer  nearly  impervious  to  the  nutritious  material 
inside.  In  these  modes  of  cooking,  it  is  often  very  desirable 
to  reduce  the  heat  applied  after  the  first  few  minuter,,  so  that 
the  interior  may  be  more  gradually  cooked ;  this  is,  perhaps, 
especially  true  in  broiling. 

Frying,  as  ordinarily  done,  is  not  a  good  mode  of  cooking, 
in  fact,  is  often  very  bad,  as  the  food  is  frequently  penetrated 
with  fat,  and  rendered  very  indigestible.  But  true  frying, 
that  is,  by  immersion  in  boiling  fat,  is  a  good  mode  of  cook- 
ing. This  coagulates  the  albuminous  substance  on  the  out- 
side, keeps  in  the  nutritious  juices,  and  prevents  soaking 
with  the  fat.  Often  the  food  to  be  thus  cooked  is  first  coated 
with  white  of  egg,  which  is  very  quickly  coagulated,  and 
helps  form  a  protecting  outside  crust. 

Cooking  starch  causes  the  starch  grains  to  swell  and  burst, 
and  makes  the  starch  much  more  digestible. 

(For  further  information  read,  in  the  Appendix,  the  ex- 
tended quotations  from  Mrs.  Abel.) 


194  OBJECT  OF  DIGESTION. 


THE    DIGESTIVE    SYSTEM. 

The  tissues  are  worn  out  by  their  oxidations.  They  are 
built  up  again  by  the  blood,  and  the  blood  is  renewed  by  the 
food. 

All  food  must  be  reduced  to  the  liquid  condition,  if  it  is 
not  already  liquid. 

The  chief  organ  in  this  work  of  liquefying  the  food  is  the 
Digestive  Tube,  or  "  alimentary  canal  "  as  it  is  called.  As  the 
food  passes  through  the  digestive  tube,  it  is  subjected  to 
various  mechanical  and  chemical  processes,  which  liquefy  it, 
and  bring  it  into  such  a  condition  that  it  can  be  absorbed  by 
the  mucous  lining  of  the  digestive  tube  and  passed  into  the 
blood. 

To  take  a  special  instance,  a  muscle  is  in  part  worn  out  by 
the  oxidation  during  its  activity ;  to  replace  the  loss  suppose 
we  take  a  piece  of  steak.  We  cannot  substitute  this  directly 
in  the  place  of  the  worn-out  tissue.  In  digesting  the  steak 
we  must  tear  it  all  to  pieces,  and  reduce  it  to  a  liquid  form 
by  the  action  of  the  teeth  and  by  the  various  liquids  from 
the  glands  along  the  digestive  tube.  In  short,  the  muscle,  as 
such,  must  be  thoroughly  destroyed ;  in  the  liquid  produced 
by  the  digestion  of  the  beef,  there  is  no  trace  whatever  of  the 
structure  of  the  beef.  But  the  blood,  taking  this  material, 
builds  muscle  which  can  hardly,  if  at  all,  be  distinguished 
from  the  original  beef. 

If  the  food  taken  be  all  ready  to  build  tissue,  for  example, 
certain  forms  of  sugar,  liquid,  soluble,  and  of  the  proper 
chemical  composition,  it  will  not  need  to  go  through  these 
changes. 

In  order  to  understand  the  process  of  digestion,  let  us 
first  turn  our  attention  to  the  anatomy  of  the  organs  of  diges- 
tion. 


ABDOMINAL    ORGANS.  195 

Organs  of  the  Abdominal  Cavity.  —  (Rabbit  or  cat.) 

1.  Slit  the  skin  in  the  middle  line  from  the  breast-bone  to 
the  pelvis,  and  strip  it  well  back  to  the  sides.     Observe  the 
thin  Abdominal  Muscles,  which  form  the  ventral  wall  of  the 
abdomen.     Carefully  slit  this  in  the  middle  line  from  the  pel- 
vis  to  the   breast-bone ;    from    the    middle    of   this    slit    cut 
outward  on  each  side,  and  turn  back  the  flaps. 

2.  The   lining  of  the  abdomen   is  the  Peritoneum ;  draw 
the  tips  of  the  fingers  over  it  to  learn  its  smoothness. 

3.  Observe  the  coiled  Intestine,  noting  any  variations  in 
size,  shape,  or  markings,  but  do  not  now  move  any  part  from 
its  natural  position.     In  a  recently  killed  animal  the  intes- 
tines usually  show  a  slow  motion,  like  that  of  a  mass  of 
earthworms,  coiled  and  crawling  over  each  other.     This  is 
the  Peristaltic  motion,  due  to  the  shortening  and  relaxation 
of  the  muscles  in  the  walls  of  the  intestines.     This  is  always 
a  wave-like  motion,  proceeding  from  the  anterior  toward  the 
posterior  end  of  the  intestine. 

4.  In  the  anterior  part  of  the  abdomen  the  dark-colored 
Liver  may  be  seen,  overlapping  the  Stomach ;  and  in  the  hinder 
part  of  the  abdomen  the  Bladder  may  be  seen,  varying  greatly 
in  size  and  appearance  according  to  the  state  of  distention. 

5.  Pull  the  intestine  backward,  and  make  out  the  shape, 
size,  position,  and  color  of  the  stomach.     Care  must  be  taken 
in  handling    the  liver.      Its  tissue  is   so  delicate  that  it  is 
easily  ruptured  ;  and  the  organ  is  so  full  of  blood  that  enough 
may  soon  escape  to  make  the  dissection  unsightly,  and  to 
obscure  some  of  the  organs.     Do  not  touch  the  liver  with  the 
dissecting  instruments,  not  even  with  the  handle  of  the  scal- 
pel;   and   in  handling  it  with  the  fingers,  take  care  not  to 
lacerate  it  with  the  nails.    Observe  how  the  liver  and  stomach 
fit  together ;  push   the  liver  forward,  and  turn  the  stomach 
back  to  find  a  white  tube  entering  its  anterior  surface ;  this  is 


196  ABDOMINAL   OliGANS. 

the  gullet,  or  Esophagus.     At  the  larger  end  (to  the  left)  of 
the  stomach  is  a  deep  red  body,  the  Spleen. 

6.  Find  now  the  connection  between  the  stomach  and  the 
intestine.     Make  a  drawing  of  the  stomach,  showing  its  shape 
and  the  connection  with  the  gullet  and  the  intestine. 

7.  Trace  the  intestine ;  that  part  which  forms  a  long  loop 
near  the  stomach  is  the  Duodenum.     Within  this  loop  is  an 
irregular,  pinkish,  or  fatty-looking  mass,  the  Pancreas.     Find 
the   Pancreatic   Duct   entering  the  intestine.      This   is    more 
easily  found  in  the  dog. 

8.  Observe  that  the  intestine  is  held  by  a  thin  membrane, 
in  which  are  branching  blood  tubes ;   this  is  the  Mesentery ; 
find  its  supporting  attachment.      In  tracing  its  course,  drag 
the  intestine  out  of  the  abdominal  cavity,  but  do  not  tear  the 
mesentery. 

9.  Observe  that  the  Small   Intestine  runs  into  the  Large 
Intestine  at  a  right  angle  near  the  beginning  of  the  large  intes- 
tine.     The  blind   end  of  the    large  intestine,   back    of   the 
entrance  of  the  small  intestine,  is  the  Cecum.     In  the  rabbit 
it  is  long,  in  the  cat  short. 

10.  Turn  the  liver  forward,  and  find,  on  its  posterior  sur- 
face, the  dark  Bile-sac.     The  Bile-duct,  by  which  the  bile  is 
conveyed  into  the  intestine,  may  be  traced  by  cutting  into  the 
bile-sac,  and  probing  with  a  bristle  tipped  with  sealing-wax. 

11.  Pull  the  liver  back,  and  examine  the  thin  muscular 
partition,  the  Diaphragm,  which  extends  across  the  body,  sep- 
arating the  chest  cavity,  or  thoracic  cavity,  from  the  abdom- 
inal cavity. 

12.  Note  the  passage  of  the  gullet,  aorta,  and  postcaval 
vein  through  the  diaphragm. 

13.  Attached  to  the  dorsal  walls  of  the  abdomen  are  the 
dark-colored,  bean-shaped  Kidneys. 

Tie  the  gullet  in  two  places  half  an  inch  apart,  and  cut 


SECTION  OF  ABDOMEN. 


197 


through  between  them.  Do  the  same  with  the  hinder  part  of 
the  large  intestine,  the  Rectum,  and  sever  it.  Kemove  the 
stomach  and  intestines,  carefully  cutting  the  mesentery  -along 
the  whole  attachment  to  the  intestines,  and  uncoil  the  latter. 
How  many  times  is  the  length  of  the  body,  including  the 
head,  contained  in  the  length  of  the  intestine  ?  Compare  the 
lengths  of  the  small  intestine,  cecum,  and  large  intestine. 
Cut  out  about  an  inch  of  the  small  intestine  in  the  middle  of 
its  course,  slit  it  open  lengthwise,  wash  it  thoroughly,  and 
with  a  lens  examine  its  inner  surface  under  water,  to  see  the 
thread -like  projections,  or  Villi.  In  the  same  way  examine  a 
piece  of  the  large  intestine.  These  points  may  be  made  out 
in  the  intestine  of  a  dog, 
or,  still  better,  from 
specimens  of  the  calf's 
intestine  obtained  from 
the  butcher. 

To  illustrate  the  re- 
lation of  the  mesentery 
to  the  intestine,  suspend 
the  arm  in  a  sling  made 
of  a  handkerchief ;  press 
the  two  thicknesses  of 
the  cloth  together  just 
above  the  arm  to  repre- 
sent the  two  layers  of 
the  mesentery.  A  more 

complete  representation  may  be  made  as  follows  :  Material : 
piece  of  large  (one  inch  or  more  in  diameter)  rubber  tubing, 
eight  inches  long;  sheet  of  thin  white  court-plaster,  six  inches 
by  twelve  inches ;  red,  blue,  a'nd  white  cord ;  lay  the  tube 
across  the  middle  of  the  court-plaster;  gum  the  plaster  snugly 
around  the  tube  ;  between  the  two  adjacent  layers  of  the 


Fig.  55.     Cross  Section  of  Abdomen. 


198  THE  MOUTH. 

court-plaster,  where  they  meet  after  passing  around  the  tube, 
lay  the  three  kinds  of  cord,  each  frayed  out  at  one  end,  the 
frayed  ends  resting  upon  the  tube.  Moisten  the  court-plaster, 
and  press  the  layers  firmly  together.  The  court-plaster  should 
now  adhere  so  closely  to  the  tube  as  hardly  to  be  seen ;  and 
the  two  layers  should  seem  as  one,  in  which  appear  the  cords 
representing  the  arteries,  veins,  and  lacteals. 

The  Organs  of  Digestion.  —  The  organs  of  digestion  are 
the  digestive  tube  and  the  accessory  parts,  the  masticatory 
organs,  the  glands  in,  and  alongside  of,  the  walls  of  the  tube. 

The  parts  of  the  digestive  tube  are  the  mouth,  the  pharynx, 
the  gullet  (or  esophagus),  the  stomach,  the  small  intestine,  the 
large  intestine. 

The  Mouth.  —  In  studying  the  mouth  and  contained  or- 
gans, the  student  should  not  content  himself  with  mere  read- 
ing, but  should  carefully  examine  his  own  mouth  cavity  by 
means  of  a  hand  glass. 

We  are  apt  to  think  of  the  mouth  as  a  cavity  of  consid- 
erable size,  as  indeed  it  is  when  fully  opened ;  but  we  are  not 
so  likely  to  think  how  completely  the  cavity  is  obliterated 
when  the  mouth  is  closed.  If  one  notes  the  sensations  from 
the  mouth  when  it  is  closed,  he  will  perceive  that  the  tongue 
almost  entirely  fills  the  space,  touching  the  roof  of  the  mouth, 
and  the  teeth  in  front  and  at  the  sides. 

The  tongue  consists  chiefly  of  muscles,  extending  in  differ- 
ent directions,  thus  giving  the  tongue  a  variety  of  motions. 
The  tongue  is  the  chief  organ  of  taste,  and  is  therefore  (with 
the  sense  of  smell)  the  gatekeeper  of  the  digestive  tube.  The 
tongue  has  also  a  keen  sense  of  touch  (the  keenest  of  any 
part  of  the  body),  and  so  is  useful  in  detecting  and  removing 
any  food  particles  that  may  remain  on  the  teeth  after  a  meal. 
During  mastication  the  tongue,  with  the  lips  and  cheek,  keep 
the  food  between  the  teeth.  When  the  morsel  of  food  is 


THE   TEETH. 


199 


sufficiently  masticated,   the  tongue  pushes  it  back   into  the 
pharynx  to  be  swallowed. 

The  Teeth.  —  The  teacher  can  easily  get  a  lot  of  teeth 
from  almost  any  dentist  for  the  asking.  These  should  be 
cleaned  before  using  them  in  the  class.  Use  pearline  or  any 
washing-soda.  If  there  be  enough  time,  let  each  pupil  make 


Longitudinal  Section 


-  Enamel 


Pulp  Cavity 

Dentine 

Cement 


Side  View 


Face  View 


Crown 


-     Neck 


Root 


: Hole  for  Blood  Tubes  and  Nerves • 

Fig.  56.     Parts  of  a  Tooth.     (Incisor.) 

a  drawing  of  one  of  each  of  the  four  kinds  of  teeth ;  and  it 
would  be  well  to  draw  both  a  front  (outer  surface)  and  a  side 
view  (surface  adjacent  to  another  tooth),  of  each  of  the  four 
kinds. 

The  study  of  a  single  tooth. 

1.    External  features  of  a  tooth. 

Examine  one  of  the  front  teeth.    It  has  the  following  parts  • 

1.  The  Crown,  the  part  that  is  above  the  gum. 

2.  The  Root,  the  part  that  was  buried  beneath  the  gum. 

3.  The  Neck,  a  more  or  less  constricted  part,  dividing 
the  crown  from  the  root ;  it  is  normally  at  about  the  surface 
of  the  gum. 

4.  A  Hole  at  the  tip  of  the  root. 


200  STRUCTURE  OF  A    TOOTH. 

2.    Structure  of  a  tooth. 

Let  eacli  pupil  prepare  a  longitudinal  section  of  a  tooth 
as  follows  :  Imbed  a  tooth  in  a  little  sealing-wax  on  the 
end  of  a  spool,  cork,  or  block  of  wood.  With  a  grindstone 
grind  away  one  half,  showing  the,  pulp  cavity  to  the  tip  of  the 
root  as  in  Fig.  56.  If  human  teeth  cannot  be  obtained,  almost 
any  kind  will  serve.  Let  each  pupil  keep  his  preparation.  The 
following  parts  should  be  clearly  distinguished  :  — 

1.  The  Pulp-cavity,  communicating  with  a  hole  in  the 
tip  of   the   root,   through   which    the   nerve  and   blood-tube 
entered. 

2.  The  bulk  of  the  tooth  is  made  up  of  a  substance 
called  Dentine  (ivory). 

3.  The  crown  of  the  tooth  has  a  covering  of  Enamel,  a 
very  hard  substance. 

4.  The  root  is  covered  with  a  bony  substance  called 
Cement. 

Make  a  drawing  of  the  surface  thus  exposed,  naming  the 
parts. 

The  Kinds  of  Teeth  and  their  Arrangement.  —  Begin- 
ning at  the  middle  of  the  front  of  the  mouth,  there  are  (in 
the  normal  adult)  eight  teeth  in  each  half-jaw  :  two  Incisors, 
one  Canine,  two  Bicuspids  (or  Premolars),  and  three  Molars. 

The  kinds  and  arrangement  of  teeth  are  often  expressed 
by  a  Dental  Formula,  in  which  the  numerators  indicate  the 
upper  jaw  and  the  denominators  the  lower,  thus  :  If,  C}, 
PMf,  MJ  (for  one  side  of  the  head). 

The  crown  of  an  incisor  is  chisel-shaped ;  but  the  root  is 
flattened  in  the  opposite  direction,  i.e.,  at  right  angles  to  the 
jaw,  instead  of  parallel  to  it,  as  is  the  case  with  the  crown. 
If  possible,  have  at  hand  also  a  skull  from  which  the  teeth 
have  been  extracted,  in  order  to  see  the  cavities  into  which 
the  teeth  fitted. 


KINDS   OF  TEETH. 


201 


The  canine  tooth  has  a  conical  crowii,  and  a  longer  root 
than  the  incisor. 

The  bicuspid  has  two  points. 

The  molar  has  a  cuboidal  crown,  and  usually  two  or  three 
roots. 


KINDS  OF  TEETH 
Incisors     :::: 


TIME  OF  APPEARANCE 
7th  Month 
9th      " 
18th      " 


Incisors „.. 

Canine 

Bicuspids     ....... 


Molars 


TEMPORARY  SET 
Upper 


7th  Year 
8th      " 

nth    " 

9th     " 


.     .  Lower 

PERMANENT  SET 
Fig.  57.     TEETH :  Kinds,  Arrangements,  and  Times  of  Appearance. 

The  thirty-two  teeth  of  the  permanent  set  were  preceded 
by  a  temporary  set  of  twenty  Milk  Teeth. 

Because  the  first  set  is  temporary,  it  should  not  therefore 


202  CARE  OF  THE   TEETH. 

be  neglected.  Cavities  in  these  should  be  filled  and  the  teeth 
kept  clean. 

Before  the  temporary  set  has  gone,  the  first  of  the  per- 
manent set  appear.  The  first  of  these,  often  called  the  "  six- 
year  molars/'  are  just  back  of  the  hindermost  "milk  molars." 
These  should  receive  especial  care,  as  they  will  never  be  re- 
placed. Any  beginning  of  decay  in  them  ought  to  receive 
prompt  attention. 

The  Care  of  the  Teeth.  —  The  teeth  need  careful  atten- 
tion. They  should  be  thoroughly  brushed  at  least  twice  a 
day,  on  rising  and  on  going  to  bed.  It  would  be  better  to 
clean  them  after  each  meal  also.  If  a  tooth  powder,  recom- 
mended by  a  reliable  dentist,  is  not  used,  a  good  white  castile 
soap  will  serve  well.  It  is  better  to  use  tepid  water. 

If  the  teeth  are  not  thoroughly  cleansed,  the  particles 
of  food  which  remain  will  soon  begin  to  decay.  This  decay 
is  caused  by  the  growth  of  germs,  usually  some  kind  of  bac- 
teria; and  the  decay  thus  begun  is  likely  to  develop  acids 
which  attack  the  limy  material  of  which  the  teeth  are  com- 
posed. When  it  is  necessary  to  take  acid  medicines,  care 
should  be  taken  not  to  let  them  come  in  contact  with  the 
teeth.  Sweet  substances  are  very  likely  to  decompose  and 
form  acids ;  so  we  must  clean  the  teeth  after  eating  candies, 
etc. 

Toothpicks  are  useful  in  removing  the  larger  particles. 
But  in  using  the  toothpick  care  should  be  taken  not  to  dis- 
lodge fillings. 

The  teeth  should  be  examined  twice  a  year  by  a  dentist, 
and  any  cayities  promptly  filled. 

Dissection  of  the  Head  of  the  Rabbit.  —  Remove  the 
skin  from  the  head. 

1.  Below  and  back  of  the  ear  is  an  irregular  pink  mass, 
the  Parotid  Salivary  Gland.  The  duct  which  conveys  its  secre- 


SALIVARY  GLANDS. 


203 


tion  runs  forward  over  the  cheek  and  opens  on  the  inside 
of  the  cheek.  It  is  hard  to  trace  in  the  rabbit.  Find  it 
in  the  dog,  slit  into  it  with  fine  scissors,  and  push  a  black 
bristle  forward  through  it  to  find  its  opening  in  the  mouth. 

2.  Just  back  of  the  angle  of   the  lower  jaw  observe  a 
roundish  body,  the  Submaxillary  Salivary  Gland.     In  the  dog 
trace  its  duct  as  in  the  case  of  the  parotid. 

3.  Observe  the  muscle  which  covers  the  outside  of  the 
back  part  of  each  lower  jaw.     This  is  the  Masseter  Muscle. 
Place  the  fingers  on  the  angle  of  your  own  jaw,  and  note  the 


Mucous  Membrane 


Duct  of  Gland 


Secreting  Cells 


Fig.  58.     Diagram  of  a  Salivary  Gland.     (After  Landois  &  Stirling.) 

action  of  the  masseter  muscle  in  shutting  the  teeth  firmly 
together.  In  the  rabbit  note  the  attachment  of  the  masse- 
ter to  the  under  edge  of  the  cheek-bone.  Trim  the  muscle 
entirely  away. 

4.  After  removing  the  submaxillary  glands  a  muscle  will 
be  found  on  each  side,  having  its  origin  on  the  inside  of  each 
half-jaw  near  their  junction.  These  are  the  Digastric  Muscles ; 
they  depress  the  lower  jaw.  Cut  away  all  the  muscles  and 
other  connection,  and  remove  the  whole  of  the  lower  jaw. 


204  SALIVARY  GLANDS. 

5.  In  the  human  skull  study  the  joint  by  which  the  lowtrr- 
jaw  is  articulated. 

6.  The    masseter    muscle    passes   from  the   angle    of   the 
jaw  to  the  lower  border  of  the  bridge,  or  arch,  of  the  cheek- 
bone. 

7.  The  temporal  muscle  is  attached  to  the  thin  wing  or 
process  of  the  jaw  in  front  of  the  hinge,  and  passes  up  inside 
of  the  arch  of   the  cheek-bone  to  spread   over  the  temple. 
Place  the  tips  of  the  fingers  on  the  temples,  and  shut  the 
teeth  firmly  together.     The  hardening  of  the  temporal  muscle 
is  felt. 

8.  Find  the  hole  on  the  inside  of  each  half-jaw  where  the 
nerves  and  blood-tubes  entered  to  supply  the  teeth. 

The  Salivary  Glands  make  the  Saliva  and  pour  it  into  the 
mouth.  There  are  three  pairs  of  salivary  glands, —  the  Parotid, 
just  back  of  the  angle  of  the  jaw,  under  the  ear  ;  its  duct 
runs  forward  under  the  skin  of  the  cheek,  and  opens  on  the 
inside  of  the  cheek  opposite  the  second  molar  of  the  upper 
jaw.  The  Submaxillary  gland  lies  under  the  angle  of  the 
jaw  ;  its  duct  opens  under  the  tongue  near  the  front  of  the 
mouth.  The  Sublingual  gland  is  in  front  of  the  submaxillary, 
and  empties  near  the  same  place  as  the  submaxillary. 

Action  of  the  Salivary  Glands.  —  The  salivary  glands 
pour  into  the  mouth  a  liquid  which  they  manufacture  from 
materials  taken  from  the  blood.  In  structure  the  gland  may 
be  compared  to  a  bunch  of  grapes,  the  grapes  representing 
the  little  cavities,  with  a  wall  of  cells  which  make  the  saliva ; 
from  these  cavities  the  liquid  passes  into  the  individual  duct, 
represented  by  the  stem  of  a  single  grape  ;  many  of  these 
uniting  form  the  main  stem,  which  corresponds  to  the  main 
duct.  A  rich  network  of  capillaries  surrounds  the  gland  ; 
when  the  gland  is  at  work  it  receives  more  blood  ;  the  liquid 
part  of  the  blood  (plasma)  soaks  out  through  the  capillary 


ACTION  OF  SALIVA.  205 

walls  and  surrounds  the  gland  ;  it  is  now  called  lymph  ;  from 
the  lymph  the  gland  directly  gets  its  material. 

The  glands  are  doubly  dependent  on  nerve  control :  — 

1.  Through    the   control   of    the   arterial   muscles   by   the 
nerves  the  amount  of  blood  sent  to  the  glands  is  regulated. 

2.  Nerves  also  go  to  the  cells  of  the  gland  to  control  their 
activity.     When  we  taste,  smell,  see,  or  even  when  we  think 
of,  some  delicious  food  the  mouth  may  "  water,"  as  we  say ; 
i.e.,  the  salivary  glands  are,  by  reflex  action,  stimulated  to 
activity  ;    on  the  other  hand,  some  emotions,  such  as  fear, 
check  the  flow  of  saliva.     The  saliva  is  mostly  water,  and, 
when  we  are  not  eating,  serves  to  keep  the  mouth  moist.     The 
water  of  the  saliva  soaks  the  food  during  mastication,  and 
helps  the  process  of  grinding;  it  enables  us  to  taste  by  dis- 
solving any  food  that  is  soluble  ;    it  further  enables  us  to 
swallow  what  would  otherwise  be  a  dry  powder.     The  special 
element  of  the  saliva,   Ptyalin,  has  the  power  of   changing 
starch  to  sugar. 

Besides  the  salivary  glands,  there  are  great  numbers  of 
simple  glands  in  the  Mucous  Membrane  lining  the  mouth. 
These  secrete  a  glairy  substance  called  Mucus. 

The  amount  of  saliva  secreted  daily  is  estimated  at  three 
pints.  Of  course  the  glands  should  be  allowed  to  rest  be- 
tween meals.  The  habit  of  chewing  gum,  though  supposed 
to  aid  digestion,  undoubtedly  does  far  more  harm  than  good. 
During  the  resting  period  the  glands  accumulate  material  for 
the  active  work  of  secretion  ;  for  there  is  no  sac  in  which  to 
store  the  saliva,  and  it  must  be  made  as  fast  as  it  is  needed. 

"  The  character  of  action  of  salivary  ferment  is  further 
defined  by  experiments  showing  :  1,  that  it  is  destroyed  by 
boiling;  2,  that  its  action  is  delayed  or  suspended  at  a  low 
temperature,  most  pronounced  at  about  body  temperature 
(37°  C.) ;  3,  that  it  acts  best  in  a  neutral  or  in  a  faintly  alka- 


206  ACTION   OF  SALIVA. 

line  medium,  not  at  all  in  an  acid  medium,  or  in  too  strong 
an  alkaline  medium;  4,  that  it  has  almost  indefinite  power, 
if  the  product  of  its  own  action  (sugar)  is  not  suffered  to 
accumulate.  In  all  these  respects,  with  the  exception  of  the 
third,  the  salivary  ferment  resembles  ferments  in  general, 
which  are  destroyed  by  heat,  delayed  by  cold,  and  are  limited 
in  their  action  only  by  the  accumulated  product  of  such 
action."  —  WALLER. 

Ptyalin  is  a  type  of  a  group  of  bodies  called  Unorganized 
Ferments,  or  Enzymes.  These  ferments  are  the  agents  that 
produce  the  peculiar  chemical  changes  that  are  the  chief  part 
of  digestion. 

EXPERIMENTS    WITH    THE   DIGESTIVE    LIQUIDS. 

Label  all  the  test  tubes  used  in  these  experiments. 
The  action  of  the  Saliva  on  starch. 

1.  Make  a  starch  paste  as  follows  :  Place  one  gram  of 
starch  in  a  mortar,  and  rub  up  well  with  a  little  cold  water. 
Add  two  hundred  c.  c.  of  boiling  water,  and  boil  for  some 
time,  stirring  well. 

2.  Prepare  a  solution  of  grape  sugar  by  crushing  a  few 
raisins  and  soaking  them  in  water.     To  half  a  test  tubeful  of 
this  solution  add  three  or  four  drops  of  solution  of  caustic 
potash  and  two  or  three  drops  of  a  dilute  solution  of  copper 
sulphate  (blue  vitriol)  ;  or,  instead  of  using  the  caustic  potash 
and  copper  sulphate,  use  "  Fehling's  test  tablets,"  which  can 
be  bought  of  the  druggist.     Shake  the  liquid  and  boil.     An 
orange-red  precipitate  indicates  the  presence  of  grape  sugar. 

3.  Collect  a  teaspoonful   of   saliva  in    each  of   five  test 
tubes ;  add  water  till  the  tubes  are  half  full.     Label  the  tubes 
A,  B,  C,  D  and  E.     Boil  the  liquid  in  test  tube  A. 

4.  Add  a  few  drops  of  the  starch  paste  to  each  of  the 


ACTION  OF  GASTRIC  JUICE.  207 

test  tubes.  Set  D  and  E  in  ice-water.  To  B  add  a  few 
drops  of  hydrochloric  acid.  Set  A,  B,  and  C  in  water  kept 
at  100°  F.  After  ten  minutes,  test  A,  B,  C,  and  D  as  in 
Exp.  2.  In  A  boiling  destroyed  the  power  of  the  saliva.  In 
B  the  acid  prevents  action  as  in  the  stomach.  C  shows  grape 
sugar.  D  shows  no  change. 

5.  Transfer  E  to  warm  water  for  ten  minutes,  then  test  to 
show  that  cold  has  not  killed  the  saliva,  but  merely  arrested 
its  action. 

6.  Test  the  action  of  saliva  on  raw  starch,  conditions  as 
in   C. 

1.  Test  both  the  saliva  and  the  starch  separately,  to  show 
that  there  is  no  sugar  in  them. 

The  action  of  the  Gastric  Juice. 

Buy  some  pepsin  of  the  druggist.  Boil  an  egg  hard,  and 
thoroughly  mince  part  of  the  white,  best  by  rubbing  it  through 
a  sieve.  Add  pepsin  to  a  little  of  the  egg  in  each  of  four 
test  tubes  half  full  of  water.  Label  A,  B,  C,  and  D.  To  B 
add  bicarbonate  of  soda,  to  C  and  D  a  few  drops  of  dilute 
hydrochloric  acid.  Set  A,  B,  and  C  in  warm  water,  and  D  in 
ice-water.  Shake  the  tubes  frequently. 

Eepeat  C  with  large  pieces  of  egg  to  see  the  effects  of 
imperfect  mastication. 

Try  also  pepsin  that  has  been  boiled. 

Pepsin  may  be  obtained  by  dissecting  off  the  mucous  coat 
of  a  pig's  stomach,  mincing,  and  soaking  it  in  glycerin  for  a 
day  or  two,  and  straining. 

Action  of  the  Pancreatic  Juice. 

The  pancreatic  juice  may  be  extracted  from  a  fresh  pan- 
creas (taken  from  a  pig)  by  mincing  the  pancreas,  and  soaking 
it  in  water  for  a  few  hours.  But  it  will  probably  be  more 
satisfactory  to  buy  from  the  druggist  preparations  of  Pancre- 
atin  and  Amylopsin. 


208  ACTION  OF  PANCREATIC  JUICE. 

1.  Emulsifying  effects  of  Pancreatic  Juice. 

Chop  a  pig's  pancreas  fine,  and  just  cover  with  water. 
A'fter  two  or  three  hours  strain  off  the  water.  Take  half  a 
test  tubeful  of  this  extract,  and  add  half  its  volume  of  olive- 
oil.  Shake  them  thoroughly  together.  This  will  form  a 
creamy  mixture,  an  Emulsion. 

Shake  oil  and  water  together  in  a  test  tube.  They  soon 
separate.  Now  add  a  little  white  of  egg  and  shake  again. 
A  more  permanent  emulsion  is  formed. 

2.  The  action  of  the  Pancreatic  Juice  on  starch. 

Prepare  starch  paste  as  before.  Add  amylopsin  now  in- 
stead of  saliva,  and  keep  in  a  warm  place,  about  the  temper- 
ature of  the  blood  or  somewhat  warmer. 

Add  hydrochloric  acid  and  sodium  bicarbonate  as  in  the 
above  experiment. 

Test  the  result  as  in  the  case  of  saliva.  It  will  be  easier 
to  use  the  amylopsin  than  to  prepare  the  extract  of  pancreas 
for  one's  own  use,  as  there  are  excellent  preparations  in  the 
market. 

3.  The  action  of  the  Pancreatic  Juice  on  Proteids. 

Take .  some  hard-boiled  white  of  egg  and  chop  fine,  or  rub 
through  a  sieve.  Put  some  of  this  into  two  test  tubes ;  half 
fill  with  water;  add  pancreatin.  To  one  add  a  little  dilute 
hydrochloric  acid,  and  to  the  other  a  little  sodium  bicarbon- 
ate. Set  both  in  a  warm  place  and  shake  frequently.  The 
effect  of  temperature  may  be  tested  as  before.  If  pancreatin 
is  not  at  hand,  make  a  glycerin  extract  of  pancreas  as  fol- 
lows :  "  Obtain  a  fresh  pig's  pancreas.  Lay  aside  in  a  cool 
place  twenty-four  hours.  Mince,  and  extract  for  two  days  in 
twice  its  bulk  of  glycerin.  Strain  off  the  glycerin  extract. 
Dilute  the  glycerin  extract  with  ten  times  its  bulk  of  water." 

Put  into  this  some  hard-boiled  white  of  egg,  and  keep  in 
a  warm  place.  To  one  test  tube  add  a  little  dilute  hydro- 


IMPERFECT  MASTICATION.  209 

chloric  acid,  and  add  to  another  some  bicarbonate  of  sodium. 
Find  also  the  effect  of  first  boiling  the  pancreatic  preparation. 

In  these  experiments  we  find  that  saliva  turns  starch  to 
grape  sugar,  if  not  in  an  acid  solution  and  if  at  the  proper 
temperature.  That  pepsin  dissolves  proteids  in  an  acid  (hy- 
drochloric) at  the  right  temperature.  The  proteid  is  turned 
to  peptone,  and  becomes  soluble  and  diffusible,  capable  of 
absorption  through  the  walls  of  the  stomach  and  intestine. 

We  find  that  the  different  elements  of  the  pancreatic  juice 
can,  in  alkaline  solution,  and  at  the  right  temperature,  emul- 
sify fats,  turn  proteid  to  peptone,  and  convert  starch  into 
grape  sugar. 

The  Bad  Effects  of  Imperfect  Mastication.  —  If  we 
swallow  food  before  it  is  thoroughly  ground  and  mixed  with 
the  saliva,  the  stomach  and  other  parts  of  the  digestive  organs 
will  require  much  more  time  to  reduce  the  food  to  a  liquid 
form.  Further,  when  eating  hastily,  we  are  very  apt  to  eat 
too  much.  Thus  we  may  give  the  stomach  a  double  amount 
of  material  to  handle,  and  the  material  may  not  be  half  so 
well  prepared  as  it  should  be.  The  work  thus  thrown  upon 
the  stomach  may  easily  be  made  fourfold.  Of  course  the 
organs  suffer;  and  sooner  or  later,  if  this  treatment  is  con- 
tinued, they  must  break  down. 

Not  only  mastication,  but  the  whole  process  of  digestion, 
goes  on  better  when  the  body  and  mind  are  at  rest  and  in 
a  peaceful  and  contented  condition,  as  not  only  the  salivary 
glands,  but  all  the  glands,  are  under  the  control  of  the  ner- 
vous system,  and  are  •  greatly  influenced  by  the  condition  of 
the  body.  During  a  meal,  and  for  a  short  time  before  and 
after,  all  thoughts  of  one's  occupation,  and  especially  all 
anxiety,  should  be  absolutely  dismissed  from  the  mind.  For 
those  whose  digestion  is  not  strong,  it  is  especially  desirable 
to  secure  a  period  of  rest  after  each  meal,  taking  a  lounge  or 


210 


PROCESS   OF  SWALLOWING. 


easy-chair,  closing  the  eyes,  and,  as  nearly  as  possible,  closing 
the  mind  ;  for  some,  even  a  short  nap  is  very  helpful. 

During  a  meal  there  should  be  conversation  on  topics  of 
general  interest.  "  Chatted  food  is  half  digested." 

It  is  said  that  the  people  of  the  United  States  are  nervous, 
and  eat,  as  they  do  nearly  everything,  hastily.  Deliberation 
in  eating  adds  to  dignity  as  well  as  health,  and  properly  may 
be  considered  an  evidence  of  culture. 


Hard  Palate 


Epiglottis,  Raised 

Gullet,  Closed 
Glottis,  Open 


Fig.  500.     Diagram,  Showing  the  Positions  of  the  Organs  of  the  Mouth  and 
Throat  During  Breathing. 


The  Process  of  Swallowing.  —  The  cavity  back  of  the 
mouth,  beyond  the  soft  palate,  is  the  Pharynx.  The  pharynx 
is  a  funnel-shaped  cavity,  communicating  above  with  the  pas- 
sages from  the  nostrils ;  in  front  it  opens  into  the  mouth ; 
below  it  connects  with  the  windpipe,  through  the  glottis,  and 
with  the  gullet,  which,  as  we  have  seen,  lies  just  back  of  the 
windpipe. 


PROCESS    OF  SWALLOWING.  211 

When  the  morsel  of  food  is  ready  to  be  swallowed,  the 
tongue  pushes  it  back  into  the  pharynx ;  the  soft  palate  is 
raised  to  shut  off  the  passage  into  the  nasal  cavity  ;  the  larynx 
is  pulled  upward  and  forward  ;  the  epiglottis  is  pulled  down' 
over  the  glottis,  or  opening  of  the  windpipe ;  and  the  base  of 
the  tongue  extends  back  over  the  epiglottis ;  thus  the  air  pas- 
sages, above  and  below,  are  shut  off,  and  the  food  passes  over 
the  epiglottis  into  the  gullet.  The  muscles  of  the  pharynx 


Eustachian  Tube 

Soft  Palate,  Raised 
Food 


Epiglottis,  Down 
Gullet,  Open 

Glottis,  Closed 


Fig.  59b.     Diagram,  Showing  the  Positions  of  the  Organs  of  the  Mouth  and 
Throat  During  Swallowing, 

also  do  their  part  in  pushing  the  food  along.  As  soon  as  the 
food  has  passed  over  the  epiglottis,  the  epiglottis  rises  to  its 
upright  position,  and  the  soft  palate  drops  back  to  its  place, 
leaving  the  air  passages  again  open.  As  we  are  swallowing 
only  a  small  part  of  the  time,  the  passageway  naturally  stands 
open  to  the  air ;  and  when  we  swallow,  the  parts  are,  by  mus- 
cular effort,  temporarily  adjusted  for  this  work.  It  is  to  be 


212  THE  STOMACH. 

observed  that  the  food  tube  and  the  air  tube  cross,  and  that 
the  pharynx  is  their  crossing.  There  is  a  spring  switch  (to 
borrow  a  term  from  the  railway)  which  keeps  the  track  open 
for  the  air,  which  is  all  the  time  passing ;  but  when  the  food 
comes  along,  the  switch  must  be  held  open  until  it  has  passed. 

As  we  saw  when  we  examined  the  gullet,  it  has  an  outer 
muscular  coat,  and  an  inner  mucous  coat.  The  muscular  coat 
has  two  layers,  an  inner  with  circularly  arranged  fibers,  and 
an  outer  layer  with  longitudinally  arranged  fibers.  When  the 
food  enters  the  gullet  the  muscle  fibers,  especially  the  circular 
fibers,  shorten,  and  by  a  wave-like  action  push  the  mass  rap- 
idly along  into  the  stomach. 

The  passage  of  the  food  through  the  gullet  may  be  illus- 
trated as  follows  :  Let  several  persons  hold  a  large  rubber 
tube  with  their  hands  in  contact.  Put  an  egg-shaped  piece  of 
wet  soap  in  the  tube.  The  first  hand  is  shut,  and  pushes  the 
soap  along  into  the  part  of  the  tube  held  by  the  next  hand ; 
this  hand  now  compresses  the  tube,  while  the  first  hand 
remains  clinched;  and  so,  in  turn,  the  object  is  pushed  the 
whole  length  of  the  tube. 

The  first  part  of  swallowing  is  voluntary,  but  after  the 
bolus  has  entered  the  gullet  the  action  is  involuntary. 

The  mucous  lining  of  the  gullet  has  many  mucous  glands, 
which  lubricate  the  passageway  by  the  mucus  which  they 
secrete. 

The  Stomach.  —  Just  beyond  the  diaphragm  the  diges- 
tive tube  widens  suddenly,  forming  the  stomach ;  the  stomach 
is  an  oval  sac  lying  just  beneath  the  diaphragm,  with  the 
large  end  to  the  left  and  the  small  end  to  the  right.  The 
smaller  end,  by  narrowing,  becomes  the  small  intestine. 
When  the  stomach  is  empty  it  collapses,  as  its  walls  are  soft 
and  flexible.  When  distended  it  may  hold  three  pints,  or 
even  more  when  abnormally  distended. 


THE  STOMACH.  213 

The  muscular  coat  of  the  stomach  consists  of  three  layers, 
distinguished  by  the  arrangement  of  the  fibers,  a  circular 
layer,  a  longitudinal  layer,  and  an  oblique  layer. 

The  mucous  lining  is  somewhat  loosely  attached  to  the 
muscular  coat,  and  when  the  stomach  collapses  the  mucous 
coat  is  thrown  into  folds,  usually  running  lengthwise. 


SMALL 

TINE 


Fig.  60.    Longitudinal  Section  of  Stomach,  Showing  Gastric  Glands  in  Position. 
(Dorsal  View.    Mucous  Coat  Unduly  Thickened.) 


If  the  inner  surface  of  the  mucous  membrane  is  examined 
with  a  lens  many  small  holes  may  be  seen.  These  are  the 
mouths  of  the  ducts  of  the  Gastric  Glands.  If  the  duct  is 
traced  inward,  it  is  found  to  divide  into  several  branches,  usu- 
ally two  or  three.  These  gastric  glands  vary  somewhat  in 
their  structure  in  different  parts  of  the  stomach.  The  liquid 
secreted  by  the  different  glands  also  varies  considerably,  but 
the  liquid  as  a  whole  is  called  the  Gastric  Juice.  The  gastric 
juice  is  chiefly  water,  containing  a  ferment,  or  enzyme,  called 
Pepsin,  and  a  small  amount  of  acid.  The  amount  of  gastric 
juice  secreted  daily  has  been  estimated  at  from  five  to  ten 


214 


GASTRIC   GLANDS. 


Mouth  of  Gland 


Epithelium 


quarts.  Of  course,  we  must  bear  in  mind  that  nearly  all  of 
this  is  again  absorbed  from  the  digestive  tube,  and  is  not  a 
permanent  loss  to  the  body. 

The  mucous  membrane  is  abundantly  supplied  with  blood 
tubes ;  but  during  the  time  of  its  rest  the  blood  flow  here  is 
diminished,  and  the  membrane  is  comparatively  pale.  But  as 
soon  as  food  is  introduced  into  the  stomach,  the  blood  flow  is 
greatly  increased,  and  the  mucous  membrane  becomes  red. 
This  blood  supply  gives  the  glands  the  materials  with  which 
they  manufacture  the  gastric  juice.  At  the  same  time  the 

cells  of  the  glands  are  stim- 
ulated to  action,  and  the 
secretion  is  poured  out 
rapidly.  The  alkaline  sa- 
liva also  aids  in  stimulating 
the  secretion  of  the  gastric 
juice.  The  special 
work  of  the  gastric 
juice  is  accom- 
plished by  the  pepsin,  aided 
by  the  acid;  these  convert 
proteids  into  a  soluble  sub- 
stance, called  Peptone,  which 
can  be  absorbed  through  the 
walls  of  the  digestive  tube 

into  the  blood.  Eennet,  used  in  cheese-making,  is  a  famil- 
iar substance  obtained  from  the  fourth  stomach  of  the  calf. 
Now,  when  milk  enters  the  human  stomach  it  is  curdled  ; 
that  is,  the  casein  previously  dissolved  in  the  liquid  milk  is 
coagulated.  This  curdling,  or  coagulation,  is  attributed  to  a 
ferment  in  the  gastric  juice  called  Rennin ;  and  it  seems  to 
be  entirely  distinct  from  pepsin.  At  the  same  time  all  the 
food  is  soaked  by  the  gastric  juice,  the  process  being  greatly 


Principal, 

Cells 


Connective  Tissue 

Fig.  81.     Three  Glands  of  the  Stomach  — 
Cardiac  Part 


ABSORPTION  FROM  STOMACH.  215 

assisted  by  the  churning  motion  of  the  stomach  caused  by 
the  action  of  the  muscular  coat.  The  food  is  thus  gradually 
reduced  to  a  pulpy  mass  called  Chyme.  During  the  first  part 
of  digestion  in  the  stomach,  the  thick  ring  of  circular  fibers 
called  the  Pylorus  (gatekeeper)  around  the  opening  of  the 
stomach  into  the  intestine,  keeps  the  passage  nearly  closed, 
leaving  a  small  orifice  for  liquids  only. 

Such  rings  of  muscular  fibers,  guarding  openings,  are 
called  Sphincter  Muscles.  There  is  a  similar  one  at  the  anal 
opening. 

But  as  the  food  is  reduced  to  the  proper  condition  the 
pyloric  muscles  relax,  and  allow  the  chyme  to  pass  into  the 
intestine.  And  at  last  any  indigestible  substances  are  allowed 
to  pass  (usually). 

The  time  required  for  the  complete  digestion  of  any  ordi- 
nary meal  is  from  three  to  four  hours ;  though  this  may  be 
much  longer  if  very  indigestible  substances  have  been  eaten, 
or  if  the  condition  of  the  body  or  mind  is  such  as  to  retard 
the  process  of  digestion. 

Some  parts  of  the  food  that  are  already  digested,  or  such 
matters  as  are  soluble,  e.g.,  water  containing  sugar,  peptone, 
salts,  etc.,  may  be  absorbed  immediately  through  the  walls  of 
the  mouth  and  stomach  into  the  blood  capillaries. 

Recent  experiments  show  that  the  amount  of  absorption 
from  the  stomach  is  much  less  than  was  formerly  supposed ; 
water,  for  instance,  "  when  taken  alone,  is  practically  not  ab- 
sorbed at  all  in  the  stomach.  As  soon  as  water  is  introduced 
into  the  stomach,  it  begins  to  pass  out  into  the  intestine,  be* 
ing  forced  out  in  a  series  of  spurts  by  the  contractions  of  the 
stomach." 

The  rest  of  the  food,  now  called  chyme,  is  passed  on  into 
the  small  intestine.  It  is  acid,  and  in  a  liquid  or  semiliquid 
condition.  Chyme,  as  it  enters  the  intestine,  is  a  mixture  of 


216 


COMPOSITION  OF  CHYME. 


digested,  partly  digested,  and  undigested  materials.  Some  of 
the  starch  has  been  changed  to  sugar,  but  only  a  small  part, 
owing  to  the  short  time  of  mastication.  (It  is  believed  that 
the  slower  mastication  in  the  herbivora  changes  much  more  of 
the  starch  to  sugar.)  The  bulk  of  the  starch  is  unchanged. 
Some  of  the  proteid  is  already  changed  to  peptone.  Part  is 
still  proteid,  while  part  is  in  an  intermediate  stage  between 
proteid  and  peptone.  Fat  is  essentially  unchanged,  but  is 
melted  by  the  heat  of  the  mouth  and  stomach,  and  is  more  or 
less  divided  into  small  drops  by  mastication  and  the  move- 
ments of  the  stomach.  For  instance,  in  eating  bread  and 
butter,  the  melting  butter  will  be  finely  mixed  with  the  bread 
as  it  is  chewed.  The  water  in  the  chyme  was  partly  taken  as 
such,  and  partly  derived  from  the  saliva  and  gastric  juice. 
There  are  also  present  ptyalin,  pepsin,  mucus,  salts,  and  some 
indigestible  substances.  At  intervals  the  sphincter  muscles 

of  the  pylorus  relax,  and  the  con- 
tractions of  the  stomach  send  the 
liquid  mixture  into  the  intestines 
by  spurts. 

The  Intestine.  —  The  small 
intestine  has  essentially  the  same 
structure  as  the  parts  of  the  diges- 
tive tube  already  studied,  namely, 
a  mucous  lining  beset  with  an  im- 
mense number  of  tubular  glands, 
called  Intestinal  Glands.  These 
secrete  a  liquid  collectively  called 
the  Intestinal  Juice,  whose  exact 
work  is  not  well  known,  but  which 
may  be  said  to  complete  the  work 

of  the  other  secretions.  The  intestines  have  also  the  mus- 
cular coats,  about  as  described.  And  the  muscular  coat  has 


Fig.    62.      Horizontal    Section 

through  the  Mucous  Membrane  of 

the  Intestine,  showing  Intestinal 

Glands    In    Transverse    Section. 

(Highly  Magnified.') 


POETAL    CIRCULATION. 


217 


the  same  work  of  mixing  the  juices  with  the   food,  and  of 
moving  it  along. 

Soon  after  the  chyme  enters  the  small  intestine  it  has 
poured  upon  it  two  liquids,  which  enter  the  intestine  in  one 
common  stream ;  these  are  the  Bile  and  the  Pancreatic  Juice. 
Two  large  compound  glands,  the  Liver  and  Pancreas,  lie  close 
to  the  stomach ;  their  ducts  join  before  they  enter  the  intes- 


Fig.  63.     Diagram  of  Portal  Circulation. 

tine  into  which  these  juices  are  emptied  a  few  inches  beyond 
the  stomach. 

The  liver,  like  the  pancreas,  receives  a  supply  of  blood 
from  the  aorta ;  but  the  liver  is  peculiar  in  receiving,  through 


218  FUNCTIONS   OF  BILE. 

the  portal  vein,  nearly  all  of  the  material  obtained  by  absorp- 
tion from  the  digestive  tube.  The  blood  from  the  portal  vein 
is  distributed  through  the  liver.  And  from  this  blood  the 
liver  manufactures  at  least  two  important  substances,  the  bile 
and  the  liver-starch,  or  Glyeogen. 

The  bile  is  secreted  all  the  time,  but  more  actively  during 
digestion.  The  part  made  while  digestion  is  not  going  on  is 
stored  in  the  bile-sac.  The  functions  of  the  bile  are  still 
poorly  understood.  But  the  following  are  believed  to  be  a 
part  of  its  work  :  — 

1.  It  is  believed  to  aid  in  emulsifying  the  fats. 

2.  It  is  supposed  to  aid  in  the  absorption  of  fat. 

3.  The  bile,  to  a  certain  extent,  is  waste  matter;   so  the 
liver  is  an  organ  of  excretion  as  well  as  an  organ  of  secretion. 

4.  It  is  found  that  if,  for  any  cause,  the  bile  is  prevented 
from  entering  the  intestine,  constipation  follows,  and  the  con- 
tents of  the  large  intestine  have  a  much  more  fetid  odor  than 
usual.     The  bile  itself  readily  putrefies ;  hence  it  is  concluded 
that  the  bile  has  no  positive  antiseptic  properties,  but  in  some 
indirect  way  retards  putrefaction. 

The  liver,  from  its  size,  ought  certainly  to  be  of  great  im- 
portance in  the  body ;  it  is  the  largest  gland  in  the  body,  and 
receives  one-fourth  of  the  blood. 

The  pancreatic  juice  acts  on  all  the  principal  classes  of 
foodstuffs :  — 

1.  A  ferment  in  it  called  Amylopsin  acts  on  starches,  chan- 
ging them  to  sugar,  even  more  energetically  than  the  ptyalin  of 
the  saliva. 

2.  Another  constituent  of  pancreatic  juice  is  Trypsin  ;  like 
the  pepsin  of  gastric  juice,  this  ferment  has  the  power  of 
cnanging  proteids  to  peptones. 

3.  The  pancreatic  juice  also  acts  on  the  fats,  in  two  ways  :  — 
(a)   It  emulsifies  them,  i.e.,  the  fat  is  divided  into  exceed- 


FUNCTIONS  OF  PANCREATIC  JUICE.  219 

ingly  fine  drops,  each  enveloped  in  a  coating  of  albuminous 
substance.  Milk  is  a  natural  emulsion.  Examine  a  drop  of 
milk  under  the  microscope.  An  emulsion  can  be  made  artifi- 
cially by  shaking  together  water,  oil,  and  white  of  egg.  The 
shaking  breaks  the  oil  into  fine  drops,  which  would  soon  gather 
again  if  no  other  substance  were  present ;  but  it  is  supposed 
that  the  albumen  forms  a  thin  coating  around  each  droplet, 
enabling  it  to  remain  distinct  in  the  liquid. 

(b)  The  fats  are  also  acted  on  chemically  by  Steapsin,  an- 
other ferment  of  the  pancreatic  juice ;  they  are  decomposed 
with  the  formation  of  free  fatty  acids,  and  thus  more  fully 
prepared  to  be  absorbed  and  to'  build  up  the  tissues.  These 
free  fatty  acids  aid  in  the  work  of  emulsifying  the  rest  of  the 
fat. 

Saliva  acts  only  on  starch ;  gastric  juice,  on  proteids ;  bile, 
on  fats ;  whereas  pancreatic  juice  acts  on  all  three,  and  prob- 
ably more  energetically  than  the  above-named  liquids. 

The  intestinal  juice  contains  a  ferment  called  Invertin, 
which  changes  cane  sugar  to  dextrose,  which  is  a  variety  of 
grape  sugar.  Dextrose  is  less  soluble  than  cane  sugar.  Here, 
then,  is  an  exceptional  case,  in  which  a  digestive  process  con- 
verts a  more  solu- 
ble substance  into  a 
less  soluble  form.  Vi,,j- 

The  bile  and  the 
pancreatic  juice  are       openings  of 
alkaline,  and  over-  Glands 

COme  the    acidity  Of  Intestinal  Glands 

the  chyme. 

Absorption. Flg-  64-    Mucous  Membrane  of  Small  Intestine, 

The   mucous   mem- 
brane of  the  small  intestine  is  thrown  into  ridges  ;  but,  unlike 
those  of  the  stomach,  they  run  transversely. 


220 


ABSORPTION —  VILLI. 


Caval  Veins 


Again,  while  the  folds  in  the  lining  of  the  stomach  are 
temporary,  these  are  permanent.  They  serve  to  increase  the 
surface  of  the  lining,  and  to  retard  the  passage  of  the  food 
material,  and  so  to  aid  the  process  of  digestion  and  of  absorp- 
tion. 

Further,  the  surface  of  the  mucous  membrane  is  thickly 
beset  with  little  cylindrical  projections,  like  the  "pile"  on 

velvet.    These  pro- 
jections are  called 
Yilli  (singular,  vil- 
lus).     Thevilli 
greatly  increase 
the  absorbing   sur- 
face of   the    small 
intestine.     In  each 
villus  is  a  network 
of   Blood   Capil- 
laries,  and    the 
beginning   of 
lymphatic  capil- 
laries called  Lac- 
teals. 

In  the  villi 
the  largest  part 
of  the  work  of 
absorption  is 
done.  The  fats 
are  absorbed  by 
the  lymph  capil- 
laries, and  the  rest  of  the  foods  by  the  blood  capillaries.  It 
should  be  carefully  noted  that  nearly  all  of  the  foods  but  the 
fats  go  at  once  to  the  liver,  through  the  portal  vein ;  but  the 
fats  are  carried  by  the  main  lymph  duct  (the  Thoracic  Duct) 


-  Portal  Vein 


Mesenteric 

Blood  Veins 

(Albumen 

Sugar) 

Capillaries 


Fig.  65.     Plan  of  Absorption. 


ABSORPTION.  221 

to  be  emptied  into  the  subclavian  vein  in  the  neck,  hence  do 
not  directly  pass  through  the  liver. 

If  a  solution  of  salt  and  one  of  sugar  are  brought  into  con- 
tact, they  will  gradually  mix  ;  and  this  is  called  Diffusion.  If, 
now,  a  piece  of  parchment  be  tightly  tied  over  the  end  of  a 
tube,  and  one  of  the  above  solutions  be  placed  inside,  and  the 
other  around  the  tube,  they  will  still  diffuse  through  the  mem- 
brane, and  mingle.  This  is  called  Osmosis,  or  Dialysis ;  and  the 
parchment  is  called  a  dialyzing  membrane.  In  the  digestive 
tube  the  mucous  membrane  represents  the  dialyzing  membrane, 
with  blood  or  lymph  on  one  side,  and  the  contents  of  the 
digestive  tube  on  the  other.  Soluble  materials,  such  as  pep- 
tones, sugars,  etc.,  pass  through  the  mucous  membrane  into 
the  blood. 

"  The  process  of  osmosis,  and  to  a  lesser  extent  of  filtration 
and  imbibition,  as  they  are  known  to  occur  outside  the  body, 
were  supposed  to  account  for  the  absorption  of  all  the  soluble 
products.  This  belief  has  now  given  way,  in  large  part,  to 
newer  views,  according  to  which  the  living  epithelial  cells 
take  an  active  part  in  absorption,  acting  under  laws  peculiar 
to  them  as  living  substances,  and  different  from  the  laws  of 
diffusion,  filtration,  etc.,  established  for  dead  membranes. 

"Unlike  sugars  and  peptones,  fats  are  absorbed  chiefly  in 
a  solid  form  —  that  is,  in  an  emulsified  condition.  There  can 
be  no  question,  in  this  case,  of  osmosis.  It  has  been  shown 
by  .nearly  all  recent  work  that  the  immediate  agents  in  the 
absorption  of  fats  are  again  the  epithelial  cells  of  the  villi  of 
the  small  intestine.  The  fat-droplets  are  taken  up  by  these 
cells,  arid  can  be  seen  microscopically  after  digestion  in  the 
act  of  passing,  or  rather  of  being  passed,  through  the  cell- 
substance.  The  epithelial  cells,  in  other  words,  ingest  the 
fat-particles  lying  against  their  free  ends,  and  then  pass 
them  slowly  through  their  cytoplasm  into  the  substance  of 
the  villus."  —  HOWELL. 


222 


LYMPHATICS. 


The  Lacteals  and  Lymphatics.  —  While  the  main  work 
of  the  lymphatics,  as  we  have  seen,  is  the  carrying  of  lymph 
from  the  tissues  of  the  body  generally  to  empty  into  the 
veins  of  the  neck,  the  lymphatics  of  the  intestines  have 
another  important  function. 

They  absorb  and  carry  the  fatty  portions  of  the  digested 


Right  Lymph  Vein 


Junction  of  Thoracic 

Duct  with  Left  Sub- 
clavian  Vein 


Main  Lymph  Vein 
(Thoracic  Duct) 


Intestine 


Lymphatic  Glands 


Fig.  66.     Lymph  Veins — Lymphatics. 

food  into  the  general  circulation.  During  most  of  the  time 
the  thoracic  duct  and  the  lymphatics  of  the  intestines  would 
hardly  be  noticed,  because  they  are  filled  with  the  clear  lymph. 


LYMPHATICS. 


223 


But  after  digestion  of  fatty  matter  they  are  rilled  with  the 
white  Chyle,  and  are  easily  seen. 

To  show  the  thoracic  duct,  feed  a  kitten  or  puppy  on  rich 
milk,  and  after  two  or  three  hours  kill  it  as  directed  on  page 
67.  As  soon  as  you  are  sure  it  is  dead,  open  the  abdominal 
cavity,  and  spread  out  the  mesentery.  The  white  lacteals, 
filled  with  chyle,  will  be  seen  radiating  through  the  mesentery. 
Press  on  some  of  these,  and  it  will  be  seen  that  they  are  thin 
tubes  filled  with  a  white  liquid.  They  converge  toward  the 
place  of  attachment  of  the  mesentery  to  the  dorsal  part  of  the 
abdomen.  On  the  dorsal  wall  of  the  abdomen,  just  posterior 
to  the  diaphragm,  the  Receptacle  of  the  Chyle,  or  the  beginning 
of  the  main  lymph  vein  (thoracic  duct),  should  be  found. 
Trace  it  anteriorly  through  the  chest  alongside  the  aorta  to 


Lacteal  with  Valves          Capillaries  Muscles  Epithelium 

Fig.  67.     Elements  Entering  into  the  Structure  of  a  Villus. 


its  mouth,  near  the  junction  of  the  left  subclavian  and  jugular 
veins. 

The  thoracic  duct  may  be  injected,  though  it  is  not  always 
easy  to  do  so.  Use  a  small  syringe  and  the  starch  preparation 
described  on  page  66.  After  finding  the  receptacle  of  the 
chyle,  snip  a  small  hole  in  its  posterior  end,  and  quickly 


224 


STRUCTURE  OF   V1LLL 


insert  the  tip  of  the  syringe  nozzle,  and  inject.  It  will  not  be 
necessary  to  ligature,  for  there  are  so  many  valves  in  the  duct 
that  if  a  fair  amount  of  the  starch  preparation  be  introduced 
there  will  be  little  reflow.  For  this  the  yellow-colored  mass 
may  be  used. 

In  each  villus  there  are  plain  muscle  fibers.  When  these 
shorten  they  squeeze  the  chyle,  that  has  already  been  ab- 
sorbed, into  the  lymph  tubes  of  the  wall  of  the  intestines, 
and  on  into  the  main  lymph  duct.  The  chyle  cannot  return 


Epithelial  Covering 


Lacteal 

Longitudinal  Mus- 
cular Fibers 

Capillary  Network 


Fig.  68.     Intestinal  Villus. 

to  the  lacteal  when  the  muscles  relax,  on  account  of  the 
valves,  similar  to  those  of  the  veins,  in  the  lacteal  at  the 
base  of  the  villus.  Then,  when  the  muscles  relax,  the  lacteal 
is  empty,  and  ready  to  absorb  more  of  the  emulsified  fat  that 
we  call  chyle. 

The  whole  digestive  tube  may  be  briefly  and  roughly 
described  as  a  muscular  tube  of  varying  diameter,  lined  by 
mucous  membrane.  The  muscular  coat  propels  the  contents 
and  mixes  them  with  liquids  ;  the  mucous  coat  is  beset  with 
glands,  making  liquids,  some  of  which  merely  soak  the  food, 
others  act  on  it  chemically,  while  mucus  serves  to  lubricate 
the  surface.  It  seerns  that  these  myriads  of  Simple  Glands 
are  not  enough,  so  several  large  Compound  Glands  lie  alongside 
the  food  tube,  and  empty  their  secretions  into  it  by  Ducts ; 


ORGANS   OF  DIGESTION. 


225 


these  supplementary  glands  are  the  salivary  glands,  the  pan- 
creas, and  the  liver. 

The  length  of  the  small  intestine  is  about  twenty-five  feet, 


Parotid  Sali- 
vary Gland 

Gullet 


Precaval  Vein 
Postcaval   Vein 


Sublingual 
Salivary  Gland 


Submaxillary 
Salivary  Gland 


Hepatic  Vein 


Mesenteric 
Vein 


--  Receptacle  of 

Chyle 
""  Lacteals 

Mesentery 


Intestine 
Fig.  69.    Diagram  of  the  Organs  Concerned  in  the  Conversion  of  Food  into  Blood. 


and  of  the  large  intestine  five  or  six  feet.  As  in  the  lower 
mammals,  the  large  intestine  is  not  a  direct  continuation  of 
the  small;  that  is,  the  small  intestine  opens  into  the  large 
near  the  beginning  of  the  latter,  so  that  there  is  a  short  blind 


226 


FOODSTUFFS   IN  A   MEAL. 


NITROGENOUS  ORGANIC 
BODIES.. 

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227 


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Epiglottis. 

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228  LARGE  INTESTINE. 

end  called  the  Cecum.  In  some  animals  this  is  large,  and  lias 
considerable  length,  but  in  man  it  is  very  short.  It  seems  to 
have  been  longer  in  man's  ancestors ;  for  there  is  a  closed  pro- 
longation of  the  cecum,  the  Vermiform  Appendix.  This  ap- 
pendix is  frequently  the  seat  of  serious  or  fatal  inflammation. 

The  large  intestine,  (joining  the  small  near  the  lower  right 
side  of  the  abdomen),  runs  upward  (ascending  colon),  crosses 
over  to  the  left  side  (transverse  colon),  and  descends  the  left 
side  (descending  colon),  and,  after  curving  somewhat  like  a 
letter  S  (sigmoid  flexure),  terminates  in  the  rectum.  It  is 
well  to  know  the  course  of  the  lower  bowel,  as  pressure  may 
be  so  applied  as  to  push  the  contents  along  in  case  the  bowels 
become  torpid. 

Most  of  the  absorption  is  accomplished  in  the  small  intes- 
tine; but  as  the  food  passes  on  into  the  large  intestine  the 
work  of  digestion  and  of  absorption  are  carried  somewhat 
farther.  If  the  residue  be  not  soon  expelled,  there  may  be 
absorption  of  some  of  the  results  of  putrefactive  changes,  and 
a  sort  of  general  poisoning  of  the  whole  body.  Hence  the 
great  importance  of  regularly  and  thoroughly  emptying  the 
lower  bowel.  The  matter  thus  expelled  is  largely  made  up  of 
indigestible  material,  with  some  real  waste  substances. 

Taking  up  again  our  comparison  of  the  body  and  a  furnace, 
we  see  that  the  feces  are  not  true  waste  products,  but  are 
rather  clinkers,  or  material  that  has  not  been  burned  or 
oxidized  in  the  body.  The  real  wastes  of  the  body  are  the 
carbon  dioxid,  urea,  water,  etc.,  that  are  thrown  off  by  the 
lungs,  kidneys,  and  skin. 

Constipation.  —  This  is  a  very  common  disorder,  and  va- 
rious evils  are  attendant  upon  it,  including  many  headaches 
and  "colds  "  as  well  as  "  piles."  Of  course,  if  any  trouble  of 
this"  kind  is  long  continued  or  severe,  a  physician  should  be 
consulted.  But  it  is  well  known  that  certain  foods  tend  to 


CONSTIPATION.  229 

bring  on  such  a  condition,  and  that  other  foods  have  the  oppo- 
site tendency.  Thus,  cracked  wheat  and  oatmeal  are  gener- 
erally  considered  as  somewhat  laxative  in  their  effects.  The 
fruits  generally  are  laxative.  The  coarse  particles  of  graham 
flour  are  irritating  to  the  mucous  lining  of  the  stomach  and 
intestines,  and  for  many  persons  serve  well  to  stimulate  the 
action  of  the  bowels.  But  in  many  persons  the  mucous  coat 
is  so  sensitive  that  it  cannot  bear  such  irritation.  For  these 
the  "entire  wheat  flour"  may  serve  the  same  purpose.  Of 
course  each  person  finds  out  by  his  own  experience  what  is 
best  for  him,  and  no  rules  can  be  laid  down  that  will  apply  to 
all  cases.  But  it  may  be  well  to  know  what  is  the  usual 
effect  of  some  of  the  common  articles  of  food,  as  perhaps  some 
persons  may  habitually  partake  of  certain  articles  and  do  not 
suspect  that  they  are  the  cause  of  the  trouble.  The  following 
list  is  taken  from  Stockham's  Tokology  (a  very  valuable  work, 
especially  for  all  mothers). 

LAXATIVE.  CONSTIPATING. 

Rolled    and   cracked  wheat   bread,  Hot  bread. 

gems,  biscuit,  griddlecakes.  White  bread. 

Crackers  and  mush  from  flour  of  the  White  crackers. 

entire  wheat  and  graharn  flour.  Black  pepper  and  spices. 

Granula.  Pastry  made  of  white  flour  and  lard. 

Bran  gruel  and  jelly.  Bread,  rolls,  dumplings,  etc.,  made 
Fruit  puddings.  with  baking-powder.' 

Fruit  pies.  Cake. 

All  fresh  acid  fruits,  including  tropi-  All  custard  puddings. 

cal  fruits,  like  bananas,  oranges,  Salted  meats. 

lemons,  etc.  Salted  fish. 

Dried  fruits.  Dried  meats. 

French  prunes  and  prunellas,  eaten  Dried  fish. 

raw.  Smoked  meats. 

Stewed  dried  fruits  containing  hydro-  Poultry. 

cyanic  acid,  of  which  peaches,  Cheese. 

plums,  and  prunes  are  the  best.  Chocolate. 

New  Orleans  molasses.  Cocoa. 


230  //  YGIENE  OF  DIG E XT  10*. 

LAXATIVE.  CONSTIPATING. 

Rhubarb.  Boiled  milk. 

Onions.  Tea. 

Celery.  Coffee. 

Tomatoes.  Coffee  made  of  wbeat,  corn,  barley, 

Cabbage,  raw.  toast,  etc. 

Corn.  Beans  (dried). 

Squash.  Potatoes. 

Cauliflower.  Farina. 

Green  peas.  Sago. 

Spinach.  Starch. 

Beets,  etc.  Tapioca. 

Liver.  Rice. 

Oysters.  Raspberries. 

Wild  game.  Blackberries. 

Hygiene  of  Digestion.  —  A  prime  requisite  for  a  good 
digestion  is  a  tranquil  condition  of  the  whole  body,  especially 
of  the  nervous  system.  We  see  that  the  blood  must  be  massed 
in  the  digestive  organs  at  the  time  of  digestion.  As  there  is 
a  limited  amount  of  blood  in  the  body,  it  is  evident  that  if 
more  is  sent  to  one  part,  other  parts  must  at  the  time  receive 
less.  If  we  try  to  study  hard  immediately  after  eating,  we 
are  calling  the  blood  away  from  the  organs  of  digestion,  and 
to  that  extent  interfering  with  the  process  of  digestion.  If 
we  exercise  the  muscles  too  vigorously  soon  after  eating,  we 
call  the  blood  to  the  muscles,  and  so  call  the  blood  away  from 
the  stomach  and  intestines.  If,  after  prolonged  study,  one  is 
unable  to  obtain  sleep,  it  may  sometimes  be  efficacious  and 
very  desirable  to  eat  a  little  of  some  very  simple  food  for  the 
purpose  of  drawing  off  the  blood  to  the  stomach,  and  thus 
relieving  the  brain.  A  little  muscular  exercise  may  accom- 
plish the  same  result,  or  a  footbath  may  be  employed.  For 
many  persons  it  would  probably  be  better  to  take  a  simple 
lunch  than  to  go  to  bed  hungry,  although  one  should  be  care- 
ful not  to  abuse  the  stomach. 


A   GOOD  DlNtfEK.  231 

It  is  exceedingly  difficult  to  lay  down  general  rules  in 
regard  to  diet.  To  a  certain  extent  each  person  must  be  a 
law  unto  himself,  for  what  agrees  well  with  one  may  act 
almost  as  a  poison  to  another.  Moderation  should  always  be 
observed,  especially  in  taking  foods  to  which  we  are  not 
accustomed. 

A  Good  Dinner.  —  Suppose  one  were  to  sit  down  to  eat 
dinner  when  ravenously  hungry.  If  in  such  a  condition  one 
begins  with  solid  food,  he  is  likely  to  eat  too  fast.  Hunger 
is  a  demand  of  the  system  for  food.  It  takes  some  time  for 
solid  food  to  go  through  all  the  processes  of  digestion,  and  be 
absorbed  into  the  system  and  appease  hunger.  But  if  a  soup 
be  first  taken,  which  is  readily  absorbed,  the  demand  of  the 
system  will  begin  to  be  met,  and  there  will  not  be  the  same 
tendency  to  rapid  eating.  Further,  a  warm  soup  stimulates 
the  blood  flow  in  the  mucous  membrane,  and  thus  prepares 
for  more  thorough  digestion.  It  is  more  easy  after  a  soup  to 
deliberately  masticate  the  solid  portion  of  a  meal.  Dessert 
and  sweetmeats,  following  a  meal,  are  often  very  helpful  by 
further  stimulating  the  secretion  of  the  glands.  Nuts,  which 
are  not  very  digestible,  are  beneficial  if  eaten  sparingly.  The 
agreeable  taste  stimulates  the  salivary  glands,  and  the  alka- 
linity of  the  saliva  stimulates  the  gastric  glands  to  increased 
activity.  The  same  may  be  said  of  cheese. 

"  Cheese  is  a  surly  elf, 
Digesting  all  things  hut  itself." 

The  average  pie  needs  some  extra  help  for  its  digestion. 
Donoghue,  formerly  champion  long-distance  skater,  when 
asked  if  he  dieted  in  preparation  for  a  race,  said  he  avoided 
pastry.  If  the  vigorous  digestion  of  a  man  skating  for  hours 
daily  in  zero  weather  cannot  profitably  manage  pie,  how  in 
the  case  of  sedentary  persons  ?  If  pie  is  eaten,  it  should  be 
masticated  with  very  great  thoroughness. 


232  TAKING   COLD. 

Hot  drink,  with  a  meal,  whether  it  be  tea,  coffee,  or  merely 
hot  water,  is  usually  beneficial ;  especially  to  a  weak  digestion, 
when  taken  before  meals. 

Undoubtedly  most  persons  would  be  better  off  if  they  did 
not  eat  puddings  and  pastries.  Fruit  is  best  taken  before 
meals,  especially  before  breakfast. 

"Taking  Cold."  —  So  long  as  one  is  actively  exercising, 
he  is  not  likely  to  take  cold.  But  if  one  rests  in  a  cool  place, 
especially  when  he  is  warm,  he  is,  as  we  all  too  well  know, 
likely  to  take  cold.  As  we  saw  when  we  were  studying  the 
circulation  of  the  blood,  the  application  of  cold  to  the  skin 
causes  the  arteries  (through  reflex  action)  to  become  smaller. 
Thus  when  resting  in  a  cool  place  the  skin  becomes  pale  and 
cold. 

During  a  "  cold  "  there  is  fever.  The  regulation  of  the 
heat  by  the  skin  is  interfered  with.  At  the  same  time  it  is 
often  noticeable  that  the  urine  is  more  abundant  than  usual. 
As  cold  may  lead  to  fatal  lung  disease,  so  it  may  be  the  be- 
ginning of  some  disease  of  the  kidneys  that  may,  in  the  end, 
bring  fatal  results. 

Diarrhea,  which  is  a  catarrhal  condition  of  the  intestine, 
may  follow,  or  be  associated  with,  a  cold ;  and  as  a  result  of 
this  the  process  of  absorption  is  often  largely  checked.  There 
is  a  great  increase  in  the  secretion  of  mucus  by  the  mucous 
glands  in  the  intestinal  wall.  As  the  various  liquids  of  di- 
gestion are  all  taken  from  the  blood,  it  is  evident  that  if  some 
returns  are  not  soon  made,  the  'system  must  become  bankrupt. 
It  is,  then,  more  easy  to  understand  the  excessive  weakness 
and  feeling  of  utter  prostration  that  we  experience  during 
an  acute  attack  of  diarrhea.  We  can  now  understand  where 
all  the  material  comes  from  to  make  the  profuse  discharges, 
especially  after  we  have  ceased  eating  for  some  time. 

It  is  a  significant  fact  that  diarrhea  is  usually  called  "  sum- 


BATHING.  233 

mer  complaint."  During  the  warm  summer  nights  we  are 
tempted  to  go  to  sleep  with  very  little  covering  over  our 
bodies.  But  it  almost  always  grows  cool  before  morning. 
The  common  summer  diarrhea  is,  in  many  cases,  due  to  bac- 
teria taken  in  food ;  but,  on  the  other  hand,  may  be  simply  a 
"  cold  in  the  bowels." 

Bathing.  —  One  purpose  of  bathing  is  to  cleanse  the  skin. 
For  this  purpose  warm  water  is  best ;  and  it  is  desirable  to  use 
soap,  especially  on  those  parts  which  are  especially  exposed  to 
contamination,  such  as  the  hands  and  feet,  the  armpits  and 
groins. 

Another  important  function  of  bathing  is  to  act  as  a  sys- 
temic tonic.  For  this  purpose  cold  bathing  is  better ;  but  this 
should  not  be  too  long  continued,  and  must  be  followed  by 
brisk  friction  to  give  the  skin  a  ruddy  glow.  For  this  kind  of 
bath  a  tub  is  not  necessary,  and  hardly  desirable.  The  water 
may  be  quickly  applied  by  means  of  a  sponge,  arid  the  body 
thoroughly  rubbed  with  a  coarse  towel.  The  whole  process 
should  be  completed  very  quickly,  especially  if  the  room  be 
not  warm. 

Instead  of  the  sponge  and  the  ordinary  form  of  towel,  it 
may  be  found  more  convenient  to  use  bath  mits  made  of  Turk- 
ish toweling.  These  are  easily  made,  and  are  somewhat  more 
convenient,  as  thus  friction  may  be  more  readily  applied  than 
with  a  towel,  which  is  apt  to  slip  in  the  hand.  The  two 
hands  may  be  used  at  the  same  time,  and  the  whole  time  of 
the  bath  need  not  exceed  two  or  three  minutes.  At  the  be- 
ginning of  a  bath,  cold  water  should  be  applied  to  the  head 
and  face. 

For  students,  or  others  who  do  not  take  a  great  deal  of 
vigorous  exercise,  which  keeps  the  skin  active,  this  means 
of  keeping  the  skin  active  is  especially  valuable.  The  use  of 
warm  water  for  cleansing  seems  best  adapted  (for  busy  people) 


234  BATHING. 

to  the  time  of  going  to  bed.  But  the  best  time  for  the  cool 
bath  is  on  getting  up  in  the  morning. 

Prolonged  warm  baths  are  debilitating,  and  probably  in- 
crease a  tendency  to  take  cold,  whereas  cold  bathing  is  one  of 
the  very  best  means  of  fortifying  against  cold,  and  especially 
against  the  tendency  to  take  cold  on  slight  exposure.  For 
most  persons  a  cool  sponge  bath,  on  rising,  will  act  as  a  most 
excellent  tonic ;  but  if  it  seems  to  produce  neuralgia,  it  should 
be  used  with  caution. 

We  have  learned  that  the  blood  supply  to  any  organ  is 
regulated  by  the  action  of  the  plain  muscle  fibers  in  the  walls 
of  the  small  arteries.  Now,  when  we  are  subject  to  changes 
in  temperature  these  muscles  get  exercise,  and  one  writer  has 
well  called  the  cold  bath  the  "gymnastics  of  the  plain  muscle 
fibers,"  and  we  can  understand  how  the  system  can  be  trained 
to  adjust  itself  to  cold,  and  enabled  to  avoid  "  taking  cold  "  so 
frequently. 

There  are  undoubtedly  many  persons  who  do  not  profit  by 
cold  bathing,  but  probably  many  of  these  would  soon  adapt 
themselves  to  it  by  beginning  with  tepid  water  and  gradually 
using  cooler.  To  stand  stripped  in  a  cold  room,  of  course,  is 
not  a  safe  thing  to  do.  And  the  great  secret  of  the  benefit 
that  may  be  expected  from  the  operation,  as  most  people  are 
situated,  is  to  be  very  brisk,  the  whole  process  occupying  only 
a  few  minutes.  Many  are  opposed  to  cold  sponge  bathing, 
and  condemn  it  without  reserve,  when,  probably,  they  have 
never  really  given  it  a  fair  trial. 

Let  it  be  repeated,  with  emphasis,  that  for  students  it  is 
one  of  the  very  best  means  of  preserving  health. 

Exercise.  —  The  full  significance  of  the  benefits  of  mus- 
cular exercise  could  not  be  understood  when  we  studied  the 
muscles,  and  before  we  had  studied  the  blood  and  its  work  in 
the  tissues  of  the  body  generally.  Now  we  can  comprehend 


EXERCISE.  235 

how  exercise  stimulates  the  cells  to  activity,  renews  the  lymph 
around  the  cells  both  by  quickening  the  blood  flow  and  by 
pressure  on  the  lymph  tubes ;  how  the  glands  of  excretion  are 
set  to  work  more  actively,  and  the  more  rapid  blood  stream 
brings  away  the  material  to  be  thrown  out. 

Exercise  is  not  merely  for  the  muscles.  It  quickens  the 
action  of  the  whole  body  by  increasing  cell  activity.  It  helps 
to  clean  out  the  system  and  to  clear  the  brain  as  welL  We 
read  Blaikie's  admirable  book,  How  to  Get  Strong,  and  learn 
not  merely  to  strengthen  the  muscles,  but  how  to  get  strong 
to  do  the  work  we  have  to  do  daily,  how  to  feel  well  every 
day,  how  not  only  to  do  our  work,  but  to  do  it  gladly,  and 
with  a  little  extra  good  cheer  that  may  radiate  from  us  and 
inspire  others.  We  have  no  right  and  no  need  always  to  carry 
the  sour  visage  of  a  devitalized  body.  Good  health  is  attain- 
able, and  ought  to  be  attained,  by  nearly  all.  Attention  must 
be  paid  to  the  laws  of  our  being.  It  takes  some  effort,  mental 
as  well  as  physical,  to  adopt  and  observe  regular  hours  for 
exercise  and  relaxation,  and  to  be  careful  in  diet. 

But  nature  rewards  for  obedience  by  the  delight  of  a 
healthy  body ;  and  she  never  forgets  and  never  forgives,  nor 
fails  to  punish  every  violation  of  every  one  of  her  laws.  Na- 
ture makes  no  threats  beforehand.  She  does  not  even  tell  us 
her  rules.  But  we  may  find  what  they  are  by  careful  obser- 
vation. 

Many  men  would  live  longer,  feel  vastly  better,  and  do 
greater  good  in  the  world,  if  they  would  take  regular  and  sys- 
tematic exercise  or  recreation  (and  this  should  be,  literally, 
re-creation).  It  is  a  short-sighted  policy  to  say,  "  I  cannot  af- 
ford the  time,"  and  mortgage  one's  future.  The  latter  half 
of  every  person's  life  ought  in  many  respects  to  be  by  far  the 
most  productive  of  good.  But  many  cut  off  this  half,  or  ren- 
der it  less  productive,  through  breaking  down  in  health  as  a 

OF  THE 

SUN.VEBSITYJ 


236  FORMS  OF  EXERCISE. 

consequence  of  trespassing  on  the  laws  of  hygiene.  Thus 
one  defeats  his  own  ends  in  life,  and  robs  the  world  of  the 
debt  he  owes  it,  that  of  returning  to  it,  in  his  riper  years, 
something  for  the  help  it  gave  to  him  in  his  early  years  while 
he  had  not  yet  reached  the  fullest  mental  maturity.  It  is  sad 
enough  that  so  magnificent  a  structure  as  the  human  body 
must  perish  and  become  part  of  the  common  clay.  But  it  is 
infinitely  more  sad  to  think  that  it  has  not  fulfilled  its  pur- 
pose when  the  end  comes  in  what  should  be  mid-career.  Each 
of  us  should  leave  the  world  better  than  he  found  it,  and  our 
ability  and  opportunities  for  doing  this  increase  as  we  reach 
middle  life. 

Forms  of  Exercise.  —  In  selecting  the  kind  of  exercise 
the  old  lines  fit  well :  — 

"In  whate'er  you  sweat,  indulge  your  taste; 
The  toil  you  hate  fatigues  you  soon, 
And  scarce  improves  your  limbs." 

Of  course  this  does  not  mean  that  a  boy  should  refuse  to 
saw  wood  because  he  dislikes  it,  and  spend  all  his  time  playing 
ball.  But  for  older  persons,  especially  those  of  sedentary  oc- 
cupation, exercise  that  exhilarates  is  far  more  beneficial  than 
that  which  is  not  enjoyed.  One  may  take  a  walk  and  carry 
all  his  cares  and  anxieties  with  him,  but  he  is  not  likely  to 
think  of  such  matters  when  placing  tennis  with  a  good  oppo- 
nent. Whether  it  be  horseback  riding,  cycling,  boxing,  boat- 
ing, or  other  form  of  exercise,  choose,  whenever  a  choice  is 
possible,  that  which  you  thoroughly  enjoy. 

Most  of  the  games  of  school  children  are  excellent  kinds  of 
exercise.  Cases  have  been  reported  of  injury  from  excessive 
skipping  the  rope.  But  in  moderate  degree  it  is  a  good  exer- 
cise. Tag,  snowballing,  racing,  the  various  games  of  ball, 
jumping,  hopping,  and  other  games  may  be  played  on  the  school 


TENNIS.  .  237 

grounds.  Tennis  is  a  splendid  game,  and  suitable  for  girls 
as  well  as  boys.  It  has  the  great  advantage  over  baseball 
that  it  does  not  require  a  large  ground  (which  often  means 
going  some  distance  from  the  school  grounds  or  from  home). 
Two  can  make  up  a  game,  and  a  little  time  can  be  better  util- 
ized than  with  the  games  requiring  more  players.  The  exer- 
cise, too,  is  more  evenly  distributed.  There  is  no  long  waiting, 
as  in  some  games,  but  a  constant  interchange  of  play,  active 
but  not  severe,  with  practically  no  danger  of  injury.  For 
those  who  can  pursue  the  more  vigorous  games  of  baseball 
and  football  they  are  admirable,  and  should  not  be  objected 
to  by  teachers  and  parents  because  occasional  injury  comes 
from  them.  No  vigorous  exercise  is  wholly  unattended  by 
risk,  though  it  is  usually  slight  when  the  proper  care  is  used. 
All  these  games  calling  for  great  activity  and  strength  develop 
manly  qualities  in  boys,  arid  do  much  to  make  them  active 
fearless  men,  men  who  in  time  of  danger  have  not  only 
strength  and  endurance,  but  well-trained  muscles,  cool  heads, 
and  brave  hearts,  men  who  know  what  to  do  and  how  to  do 
it  in  an  accident,  as  at  fires,  upsetting  of  boats,  etc.  A  few 
strong,  cool-headed  men,  by  their  presence  of  mind,  often  stop 
a  panic  and  save  many  lives  when  there  is  an  alarm  of  fire, 
which  often  proves  false. 

For  men  in  middle  life,  in  most  cases,  milder  exercises  are 
preferable,  such  as  shooting  and  fishing  and  horseback  riding. 
Every  person  should  have  some  form  of  exercise  that  takes 
him  into  the  open  air  daily.  The  English  are  more  given  to 
their  "  constitutionals  "  than  their  American  cousins,  and  are 
the  better  for  it.  Doubtless  if  we  paid  more  attention  to 
these  matters,  we  should  lose  something  of  our  national  repu- 
tation as  a  "  nervous  people."  English  women  are  noted 
walkers,  and  do  not  seem  to  pride  themselves  on  the  smallness 
of  their  feet.  The  signs  of  the  times  would  appear  to  show 


238  BOXING. 

that  we  are  improving  in  this  respect.  Probably  Americans 
make  too  much  use  of  street  cars.  Walking  is  the  cheapest 
exercise,  -and  every  one  can  afford  to  take  it.  For  those  who 
can  afford  it  horseback  riding  is  admirable.  As  Dr.  Holmes 
expressed  it,  "  Saddle  leather  is  in  some  respects  even  prefer- 
able to  sole  leather ;  the  principal  objection  to  it  is  of  a  finan- 
cial character."  Lord  Palmerston  said  "the  outside  of  a 
horse  is  the  best  thing  for  the  inside  of  a  man.'7  Bicycle  riding 
is  an  excellent  substitute.  Perhaps  livery  bills  would  prove 
cheaper  and  more  agreeable  than  doctors'  bills. 

Boxing.  —  Boxing  is  a  splendid  exercise.  It  calls  into 
play  nearly  every  muscle  of  the  body.  Many  pieces  of  appa- 
ratus in  a  gymnasium  are  for  the  especial  purpose  of  working 
certain  muscles.  But  a  pair  of  boxing-gloves  may  be  said  to 
contain  a  whole  gymnasium.  Many  kinds  of  work  in  a  gym- 
nasium are  likely  to  be  overdone,  especially  if  not  under  the 
direct  supervision  of  a  good  director.  One  may  overlift  or 
overstrain  himself.  But  in  boxing  there  is  little  tendency  in 
this  direction.  Boxing  makes  one  quick  on  his  feet,  trains  to 
quick  movements  of  the  arms,  trains  the  eye,  keeps  the  body 
in  an  erect  position,  and  especially  develops  the  muscles  of 
the  legs  and  back.  Cycling  seems  (though  an  excellent  ex- 
ercise) to  make  round  shoulders.  But  boxing  brings  out  the 
chest  and  shoulders.  It  developes  the  "  wind,"  and  keeps  one 
in  constant  action.  It  teaches  control  of  the  temper  more 
than  almost  any  other  form  of  exercise.  It  develops  a  degree 
of  self-reliance  that  is  worth  much.  Instead  of  developing  a 
tendency  to  become  involved  in  quarrels,  it  prevents  getting 
into  such  disgraceful  affairs.  The  man  who  knows  that  he 
can  defend  himself  when  it  becomes  necessary  is  far  less 
likely  to  pay  serious  attention  to  idle  bluster  and  slight  provo- 
cation than  one  not  so  trained.  And  it  may  prove  valuable  to 
know  how  to  defend  one's  self  from  the  attack  of  a  ruffian,  or 


BOXING.  239 

bully,  or  drunken  brute,  or  other  infuriated  animal.  The  cool- 
ness of  head,  the  quick  judgment,  and  prompt  action  of  a 
trained  boxer  frequently  save  one  from  serious  injury,  and 
add  not  a  little  to  personal  comfort.  Like  tennis,  boxing 
calls  for  little  apparatus,  little  space,  and  only  two  persons. 
In  many  places  where  ordinary  gymnasium  work  is  out  of  the 
question,  boxing  is  available.  It  is  indeed  a  "  manly  art "  ; 
and  the  doctrine  taught  in  Tom  Brown's  School  Days  at 
Rugby  is  as  wholesome  as  can  be  given  to  boys  to  make  them 
strong  and  active,  to  give  them  physical  and  moral  health. 

Dancing  is,  in  itself,  an  admirable  exercise.  But  the  very 
exhilaration  to  which  it  owes  one  of  its  chief  benefits  creates 
a  tendency  to  over-exercise.  As  usually  conducted,  indoors, 
frequently  prolonged  into  the  late  hours,  where  the  ventila- 
tion is  not  always  looked  after,  and  there  is  likelihood  of  tak- 
ing cold  afterward,  this  exercise  has  many  drawbacks.  If 
parents  were  wiser  they  would  see  that  this  very  attractive 
amusement  will  be  indulged  in,  sooner  or  later,  by  most  young 
people ;  and  they  would,  perhaps,  endeavor  to  regulate  what 
they  cannot  prohibit.  By  going  with  their  children,  by  see- 
ing what  company  and  what  hours  are  kept,  even  more,  by 
joining  them  so  far  as  their  age  permits,  this  beautiful  exer- 
cise would  prove  beneficial,  and  would  not  meet  the  sweeping 
(sometimes  deserved)  condemnation  which  it  now  receives  in 
many  quarters. 

In  many  of  the  older  writings  we  have  met  the  statement 
that  sedentary  persons,  especially  students,  get  a  fair  amount 
of  exercise  of  the  lower  limbs  in  walking  to  and  from  their 
daily  work,  and  that  what  they  especially  need  is  the  exercise 
of  the  arms  and  the  upper  parts  of  the  body.  But,  while  this 
is  to  a  certain  extent  true,  the  practice  has  been,  in  many 
systems  of  gymnastics,  carried  to  an  extreme.  Lagrange, 
in  his  book,  Physiology  of  Bodily  Exercise,  emphasizes  the 


240  CHOICE  IN  EXERCISE. 

point  that  the  stronger  muscles  ought  to  do  the  greater  part 
of  the  work.  The  older  view  was  that  exercise  requiring  lift- 
ing the  arms  had  a  tendency  to  promote  respiration,  and  thus 
to  aid  respiration  and  circulation.  This  is  true  to  a  certain 
extent.  But  Lagrange  makes  very  clear  that  what  is  desired 
is  to  create  what  he  calls  a  "  respiratory  need,"  that  is,  a  de- 
mand of  the  system  for  more  oxygen,  together  with  a  more 
active  getting  rid  of  waste  matters.  This  is  more  effectively 
accomplished  by  employing  the  larger  and  stronger  muscles, 
namely,  those  of  the  lower  limbs.  In  the  four-legged  animals 
the  greater  strength  and  weight  are  in  the  hind  limbs.  And 
in  man  the  lower  limbs  have  all  the  work  of  support  and  pro- 
pulsion of  the  body.  The  muscles  of  the  lower  part  of  the 
body,  being  so  large  and  powerful,  can  do  much  more  work 
without  being  overworked.  Suppose,  for  instance,  that  a  stu- 
dent has  half  an  hour  or  an  hour  for  exercise.  It  is  evident 
that  if  he  uses  the  muscles  of  the  upper  half  of  the  body  he 
cannot  do  anywhere  near  as  much  muscular  work  as  if  he  uses 
the  lower  half  of  the  body  for  the  same  length  of  time.  Com- 
pare, for  instance,  a  half  hour's  work  with  dumb-bells  with  the 
same  time  on  a  bicycle.  This  working  of  the  larger  muscles 
will  much  more  actively  stimulate  respiration  and  circulation, 
and  help  digestion  and  excretion  more,  than  the  smaller  and 
feebler  muscles  possibly  could. 

Further,  in  using  the  smaller  muscles  there  is  much  greater 
chance  of  straining  than  in  the  other  case.  Take,  for  instance, 
work  on  the  parallel  bars.  For  a  beginner  this  is  very  severe. 
It  is  making  the  upper  muscles  support  and  handle  the  whole 
weight  of  the  body,  work  for  which  they  are  not  intended,  and 
to  which  they  are  not  equal  without  a  great  deal  of  gradual 
preparation.  One  occasionally  sees,  in  a  circus,  some  per- 
former who  has  developed  the  arms  and  shoulders  out  of  all 
proportion  to  the  other  parts  of  the  body.  Nature,  in  the 


LEDGER  ACCOUNT  OF  BODY.  241 

process  of  evolution,  has  brought  man  to  the  erect  posture, 
aiid  enabled  him  to  walk  on  one  pair  of  limbs.  Now,  for  him 
to  try  suddenly  to  reverse  this  long  process  of  development 
and  walk  on  his  hands,  with  his  whole  body  up  in  the  air,  is 
doing  violence  to  his  structure,  and  is  likely,  if  followed  to 
any  considerable  extent,  to  be  attended  by  injury.  Not  that 
the  gymnastic  apparatus  is  bad ;  but  that;  in  the  main,  exer- 
cises that  conform  more  nearly  to  the  natural  condition  of 
man's  upright  position  are  more  natural,  and,  as  a  rule,  bet- 
ter. So  all  the  games  that  call  for  running,  jumping,  etc.,  are 
naturally  preferable  to  climbing,  etc. 

Ledger  Account  of  the  Body  and  its  Organs.  — 
Through  the  digestive  tube  and  lungs  the  body  receives  addi- 
tions ;  and  there  is  a  corresponding  loss  through  the  lungs, 
skin,  kidneys,  and  intestines.  So  a  ledger  account  might  be 
kept  with  the  body ;  and  it  should  balance  in  the  long  run, 
since  in  adult  life  the  weight  remains  practically  constant. 

So  we  might  take  a  single  organ,  say  the  liver,  and  balance 
its  accounts.  It  receives  a  large  amount  of  blood.  To  offset 
what  it  takes  from  the  blood,  it  gives  to  the  intestines  a  large 
quantity  of  bile,  and  to  the  blood  it  gives  glycogen. 

It  is  especially  interesting  to  note  the  losses  and  gains  of 
the  blood  as  it  passes  through  the  various  organs  of  the  body. 
A  river,  flowing  past  one  State  after  another,  will  take  some 
of  the  soil  of  each,  and  deposit  some  of  its  muddy  particles 
on  the  banks  of  each  State.  Of  course,  the  blood  is  unlike 
the  river,  in  that  it  empties  into  itself;  i.e.,  it  is  truly  a 
circulation.  The  blood  takes  something  from,  and  gives  some- 
thing to,  each  organ  as  it  flows  through  it.  From  the  intes- 
tine the  blood  gets  the  chief  part  of  its  new  material  in  the 
newly  digested  food.  To  the  muscles  the  blood  gives  nutri- 
tive material  and  oxygen,  and  receives  water,  carbon  dioxid, 
and  other  waste  matters.  The  account  would  be  a  good  deal 


242 


PLAN  OF  CIRCULATION. 


the  same  with  the  brain.     In  the  skin  and  the  kidneys  the 
blood  has  great  losses  and  little  gains. 

The  accompanying  diagrams  may  help  in  presenting  the 


Capillaries 


Vein 


Artery 


Artery 


-Vein 


Capillaries 

Fig.  72.    Diagram  of  the  Heart  and  Blood  Tubes. 
(Dorsal  View.) 

main  points  in  the  blood  circuit,  and  the  losses  and  gains  in 
its  course. 

In  the  common  blood  streams  are  combined  the  good  and 
the  bad.  The  newly  digested  food  is  received  into  a  current 
of  impure  blood  returning  from  the  muscles  (Caval  Veins). 


PLAN   OF  CIRCULATION. 


243 


The  blood  from  the  kidneys,  probably  the  purest  blood  in 
the  body,  joins  the  same  impure  stream.  From  the  Aorta,,  red 
blood,  usually  called  pure,  is  sent  to  the  kidneys  and  to  the 


Lung  Capillaries 


Pulmonary  Vein 


Pulmonary  Artery 

f-    Right  Auricle 
Right  Ventricle 

Caval  Vein 


Body  Capillaries 

Fig.  73.     Diagram  of  the  Circulation,  representing  the  Right  and  Left  Halves  separated, 
showing  that  the  Blood  makes  but  one  Circuit.    (Dorsal  View.) 

skin  to  be  purified.  Yet,  as  this  mixed  blood  flows  through 
each  organ,  that  organ,  so  long  as  it  is  in  health,  takes  from 
it  only  what  it  should  take.  The  kidney  takes,  during  health, 


244 


'/'///•;   CIRCULATION  OF  THE  BLOOD. 


PULMONARY  VEIN 
LEFT  AURICLE 


LEFT  VENTRICLE 


PULMONARY  ARTERY 

RIGHT  VENTRICLE 

IGHT  AURICLE 


Fig.  74.     Diagram  of  the  Circulation  of  the  Blood. 


A   LIVING  EDDY.  245 

only  the  waste  matters,  leaving  the  valuable  nourishing  mate- 
rial. But  in  disease  the  kidneys  may  throw  out  some  of  the 
most  valuable  portions  of  the  nutriment. 

Suppose  that  in.  a  mill,  a  workman,  whose  business  is  to 
shovel  out  wastes,  becomes  crazy,  and  shovels  wheat  or.  flour 
out  of  the  mill  into  the  stream  below.  The  diseased  kidney 
may  be  said  to  have  become  crazy,  and  in  the  disease  called 
"diabetes"  throws  out  sugar,  and  in  " albuminuria  "  excretes 
albumen.  So  with  the  other  organs,  each  seems  to  know  what 
to  take  and  what  not  to  take.  It  is  as  though  the  water  sup- 
ply of  a  city  house  was  from  the  sewer ;  each  organ  needing 
a  supply  of  building  material  acts  like  a  filter,  taking  what  it 
needs,  paying  no  attention  to  the  impurities  present,  and  the 
organs  of  waste  select  the  impurities,  allowing  the  useful  sub- 
stances to  pass  on  to  the  places  where  they  are  needed. 

A  Living  Eddy.  —  Huxley  has  very  aptly  compared  the 
body  to  an  eddy,  whose  form  remains  the  same,  but  whose 
particles  are  ever  changing. 

"  To  put  the  matter  in  the  most  general  shape,  the  body  of 
the  organism  is  a  sort  of  focus  to  which  certain  material  parti- 
cles converge,  in  which  they  move  for  a  time,  and  from  which 
they  are  expelled  in  new  combinations. 

"  The  parallel  between  a  whirlpool  in  a  stream  and  a  living 
being,  which  has  often  been  drawn,  is  as  just  as  it  is  striking. 
The  whirlpool  is  permanent,  but  the  particles  of  water  which 
constitute  it  are  incessantly  changing.  Those  which  enter  it 
on  the  one  side  are  whirled  around  and  temporarily  constitute 
a  part  of  its  individuality ;  as  they  leave  it  on  the  other  side, 
their  places  are  made  good  by  newcomers. 

"  Those  who  have  seen  the  wonderful  whirlpool,  three  miles 
below  the  Falls  of  Niagara,  will  not  have  forgotten  the  heaped- 
up  wave  which  tumbles  and  tosses,  a  very  embodiment  of  rest- 
less energy,  where  the  swift  stream  hurrying  from  the  falls  is 
compelled  to  make  a  sudden  turn  toward  Lake  Ontario. 


246  FAT. 

"  However  changeful  in  the  contour  of  its  crest,  this  wave 
has  been  visible,  approximately  in  the  same  place  and  with 
the  same  general  form,  for  centuries  past.  Seen  from  a  mile 
off,  it  would  appear  to  be  a  stationary  hillock  of  water. 
Viewed  closely,  it  is  a  typical  expression  of  the  conflicting 
impulses  generated  by  a  swift  rush  of  material  particles. 

"  Now,  with  all  our  appliances,  we  cannot  get  within  a  good 
many  miles,  so  to  speak,  of  the  living  organism.  If  we  could, 
we  should  see  that  it  was  nothing  but  the  constant  form  of  a 
similar  turmoil' of  material  molecules,  which  are  constantly 
flowing  into  the  organism  on  the  one  side  and  streaming  out 
on  the  other."  —  From  HUXLEY'S  The  Crayfish,  as  an  Intro- 
duction to  the  study  of  Zoology  as  modified  by  Sedgwick  and 
Wilson  in  their  General  Biology. 

It  will  be  well  here  to  recall  some  facts  noted  in  connec- 
tion with  the  study  of  the  blood  and  lymph.  We  then 
learned  that  the  lymph  (the  supply  and  renewal  of  which 
depends  upon  the  blood)  surrounds  the  individual  cells  which 
make  up  the  tissues  of  the  body ;  and  that,  to  a  certain  extent, 
every  cell  lives  an  independent  life,  each  taking  its  nourish- 
ment directly  from  the  lymph  around  it.  The  importance  of 
an  abundant  supply  of  good  lymph  is  now  more  apparent.  If 
digestion  is  not  good,  or  the  food  be  insufficient  or  of  poor 
quality  (whether  naturally  or  from  being  badly  cooked),  good 
blood  cannot  be  made,  and  the  lymph  will  not  be  good.  The 
cells  are  more  or  less  starved,  and  the  general  tone  of  the  body 
will  soon  be  lowered ;  for  the  health  of  the  body  as  a  whole 
depends  on  the  average  condition  of  the  cells  composing  the 
body,  just  as  the  condition  of  any  community  depends  on  the 
average  condition  of  the  individuals  of  that  community. 

Fat.  —  As  a  tissue  fat  serves  as  a  stored-up  food.  The 
camel's  hump  is  a  well-known  instance.  In  some  of  the 
savage  races  fat  is  stored  in  a  very  similar  hump.  But  in 


GLYCOGEN.  247 

most  persons  it  is  distributed  more  evenly  over  the  body, 
though  there  is  a  tendency  to  deposit  rather  more  over  the 
abdomen.  A  fat  person  can  endure  starvation  longer,  other 
things  being  equal,  than  a  thin  person. 

Hibernating  animals  are  fat  when  they  enter  upon  their 
winter  sleep,  but  are  lean  when  they  come  out  in  the  spring. 
Remaining  inactive,  they  have  produced  very  little  energy, 
their  only  motions  being  a  slow  and  feeble  breathing  and  a 
correspondingly  reduced  heart-beat.  They  have  consumed 
the  fat,  using  it  mainly  in  maintaining  the '  necessary  heat. 
In  short,  they  have  burned  their  fat  to  keep  them  warm. 

In  one  of  Captain  Mayne  Reid's  stories  (The  Plant 
Hunters)  we  are  told  how  the  hunters  followed  a  bear  into 
a  cave.  At  the  innermost  end  of  this  very  long  cave  they 
finally  killed  the  bear.  Just  at  this  time  they  find  that  their 
candles  are  all  burned  out,  and  they  are  left  in  complete  dark- 
ness, lost  in  the  bowels  of  the  earth.  Failing  to  grope  their 
way  put,  they  are  at  last  driven  to  this  expedient.  With 
what  combustibles  thay  can  gather  together,  including  their 
gunstocks  and  some  of  the  fat  of  the  bear,  they  melt  some  of 
the  fat,  they  use  the  gun  barrels  for  molds,  and  take  strips 
of  their  clothing  for  wicks,  and  make  two  long  candles.  With 
these  they  finally  light  their  way  out  to  the  upper  world. 

Now,  we  have  seen  that  when  we  burn  a  tallow  candle,  one 
of  the  chief  products  of  the  combustion  is  carbon  dioxid. 
Another  product  of  the  burning  is  common  water.  If,  then, 
these  hunters  had  left  this  bear  to  his  winter's  nap,  he  would 
have  consumed  this  fat  in  the  slow  process  of  breathing,  and 
it  would  have  given  off  the  same  products,  as  we  have  proved 
that  two  of  the  waste  matters  of  the  expired  breath  are  car- 
bon dioxid  and  water. 

Glycogen.  —  As  stated  above,  glycogen  is  formed  in  the 
liver.  This  is  indicated  by  the  fact  that  there  is  more  sugar 


248 


NUTRITION. 


in  the  blood  in  the  hepatic  vein  than  in  the  portal  vein,  except 
during  digestion.  Glycogen  is  formed  by  and  stored  in  the 
liver,  and  is  doled  out  to  the  tissues.  That  muscles  use  sugar 
in  their  action  is  indicated  in  the  fact  that  the  arteries  bring 
to  the  muscles  more  sugar  than  is  carried  away  from  them  by 
the  veins.  As  fat  is  a  reserve  food,  so  glycogen  serves  as  a 
temporary  carbohydrate  reserve. 


INORGANIC  WORLD 


Fig.  75.     Animal  and  Vegetable  Protoplasm. 

Nutrition.  —  All  the  changes  that  take  place  between  the 
reception  of  food  and  the  excretion  of  waste  are  included 
under  the  term  Nutrition.  The  materials  taken  as  food  are 
usually  more  complex  and  unstable,  the  waste  products  more 
simple  and  stable;  just  as  the  products  of  combustion  are,  as 
a  rule,  simpler  and  more  stable  than  fuels.  In  both  combus- 
tion and  the  processes  of  nutrition  the  final  result  is  oxida- 
tion, more  or  less  direct.  Since  muscles  are  the  engines  of 
motion,  and  also  are  largely  composed  of  proteid  (nitrogen- 
containing)  material,  we  would  naturally  expect  that  increased 
muscular  exertion  would  increase  the  excretion  of  urea  (the 
only  nitrogen-containing  waste).  But  experiment  shows  that 
increased  muscular  action,  such  as  mountain  climbing,  hardly 
increases  the  amount  of  urea  excreted.  Such  work,  however, 
does  largely  increase  the  amount  of  carbon  dioxid  excreted. 
It  is  thought,  therefore,  that  our  energy  is  largely  derived 
from  carbohydrate  foods  and  fats ;  and  this  view  is  strength- 


LIFE  PROCESSES. 


249 


ened  by  the  fact  that  our  beasts  of  burden  depend  chiefly  on 
carbohydrate  foods. 

"  Proteid,  by  digestion,  becomes  peptone,  which  is  absorbed 
and  retransformed  into  the  proteids  of  plasma  and  lymph. 
These  fluids  surround  and  permeate  the  organized  elements 
of  the  tissue,  and  the  proteids  that  they  carry  form  the  float- 
ing balance  of  nutritive  matter  from  which  the  comparatively 
fixed  capital  of  living  protoplasm  is  supplied.  Of  this  free, 
circulating,  or  coasting  proteid,  in  blood  and  in  lymph,  it  is 
supposed  that  only  a  small  proportion  is  actually  taken  into 
chemical  combination  in  protoplasm  as  fixed  or  organ  proteid, 
and  that  the  greater  proportion  is  acted  upon  and  used  by 
living  protoplasm  without  being  integrated  by  it  to  make 
part  of  its  own  substance.  The  free  or  coasting  proteid  thus 
used  up  gives  rise  to  urea,  as  does  that  small  proportion  of 
fixed  or  organ  proteid  which  disintegrates  and  gives  place  to 
a  correspondingly  small  proportion  of  newly  integrated  pro- 
teid." —  WALLER. 


ASSIMILATION 
CIRCULATION, 


VEGETABLE  FOOD 


ULANT     \ 
BOLISM/ 


INORGANIC  (MINERAL)  MATTER 

Fig.  76.    Life  Processes. 


While  increased  muscular  action  does  not  very  perceptibly 
increase  the  amount  of  urea  excreted,  the  amount  of  urea  is 
increased  by  increase  of  the  amount  of  proteid  food  taken. 

The  building-up,  or  constructive,  processes  are  included 


250  INDESTRUCTIBILITY  OF  MATTER. 

under  Anabolism,  while  Katabolism  designates  the  tearing- 
down,  or  destructive  processes.  All  the  processes  of  nutri- 
tion, both  of  building  up  and  tearing  down,  are  included  in 
the  term  Metabolism. 

The  Indestructibility  of  Matter.  —  We  are  agreed  that 
we  cannot  destroy  matter.  We  may  demolish  a  house,  but 
the  material  is  all  there.  We  may  burn  it ;  but  if  we  could 
gather  the  ashes  and  that  part  of  the  smoke  and  gases 
furnished  by  the  material  of  the  house,  the  weight  would 
all  be  recovered. 

In  the  continual  wasting  away  of  our  bodies,  there  is  no 
real  loss  of  matter.  Our  weight  is  reduced ;  but  the  wastes 
are  still  part  of  the  earth  or  air,  and  are  used  again.  For 
instance,  a  particle  of  carbon  in  the  carbon  dioxid  of  the 
expired  breath  may  be  taken  in  through  a  blade  of  grass  in 
an  adjoining  field.  A  cow  may  eat  the  grass,  and  we  may 
soon  take  the  very  same  particle  of  carbon  in  the  flesh  or 
milk  of  the  cow.  Or  the  carbon  may  be  taken  by  that  kind 
of  grass  called  wheat,  and  become  part  of  the  seed  or  grain  of 
wheat,  and  be  made  into  flour  and  be  eaten  as  bread,  and  be 
part  of  us  once  more.  Or  this  particle  of  carbon  might  be 
carried  by  the  winds  to  Florida  or  California,  and  become  part 
of  an  orange,  and  come  again  to  make  part  of  our  bodies. 
Thus  there  is  a  ceaseless  round  of  matter  into  and  out  of  our 
bodies.  The  plants  furnish  food  for  us,  and  we  help  to  make 
food  for  them  by  the  wastes  of  our  substance.  No  one  has  a 
monopoly  of  any  portion  of  matter ;  it  is  now  ours,  now  some- 
one else's.  A  particle  may  pass  from  one  animal  to  another 
animal,  as  when  we  eat  flesh  or  other  animal  food.  But  more 
often  the  wastes  of  our  bodies  go  to  make  part  of  the  air  or 
the  soil,  and  are  then  taken  by  some  plant  before  again  be- 
coming part  of  our  tissues.  But  we  are  as  unable  to  destroy 
matter  as  we  are  to  create  it. 


INDESTRUCTIBILITY  OF  FORCE. 


251 


The  Indestructibility  of  Force.  —  So  with  energy.  We 
cannot  create  it  and  we  cannot  destroy  it.  We  d.erive  our 
energy  from  the  food  we  eat.  And  this  food  we  get  directly 
or  indirectly  from  the  vegetable  kingdom. 

An  engine  gets  energy  from  the  combustion  of  fuel.  In 
the  growth  of  the  plant  under  the  influence  of  sunlight  the 


ANIMALS 

AND  PLANTS  NOT 
POSSESSING  CHLOROPHYLL 

WHICH  DISINTEGRATE 
COMPLEX  CHEMICAL  COM- 
POUNDS,  LIBERATING 
ENERGY  IN  THE 
PROCESS. 


PLANTS 
POSSESSING  CHLOROPHYLL 

INTEGRATE  COMPLEX 

CHEMICAL  COMPOUN 

STORING  UP  SOLAR  ENERGY 

IN  THE  PROCESS, 

THEY 


Solar  Energy 


Energy  originally  obtained  from  the  sun  radiated 
by  the  animal  (chiefly)  into  space  as  heat,  and 
thereby  becoming  ultimately  unavailable. 


Fig.  77.    /fetation  of  Plants  and  Animals. 

plant  has  stored  up  energy.  Now  that  the  wood  or  coal  are 
burned  the  energy  is  given  out,  primarily  as  heat.  But  we 
may  convert  the  heat  into  electricity,  the  electricity  into  light, 
or  back  again  into  heat  if  we  wish.  We  get  our  energy  from 
food  as  the  engine  gets  its  energy  from  fuel.  This  is  saying 
nothing  against  the  superiority  of  the  human  body,  and  is 
not  in  the  least  degrading.  We  are  self-maintaining,  self- 
directing,  growing,  living  machines.  Still,  starvation  soon 
puts  an  end  to  our  ability  to  produce  energy  of  any  kind. 

Now,  it  is  a  well-recognized  fact  that  in  very  many  ma- 
chines only  the  smaller  part  of  the  energy  is  directed  to  the 
end  sought.  Take  a  common  candle.  We  wish  to  get  light 
from  it.  But  most  of  the  energy  of  the  candle  is  devoted 


252  CONSERVATION   OF  ENERGY. 

to  making  heat,  which,  in  this  case,  we  do  not  desire.  In 
many  machines  there  is  great  loss  from  friction,  loss  by  ra- 
diating heat,  etc.  Physiologists  tell  us  that  the  human  body 
utilizes  a  larger  portion  of  its  energy  than  most  machines. 
While  energy  may  fail  to  be  used  for  the  desired  purpose, 
it  is  never  destroyed,  nor  really  lost. 

"  The  proof  of  the  facts  just  stated  has  led  to  the  estab- 
lishment of  the  grand  twin  conceptions  of  modern  science  :  — 

"  1.  That  all  kinds  of  energy  are  so  related  to  one  another 
that  energy  of  any  kind  can  be  transformed  into  energy  of 
any  other  kind,  known  as  the  doctrine  of  the  Correlation  of 
Energy. 

"2.  That  when  one  form  of  energy  disappears,  an  exact 
equivalent  of  another  form  of  energy  always  takes  its  place, 
so  that  the  sum  total  of  energy  is  unchanged,  known  as  4he 
doctrine  of  the  Conservation  of  Energy." 

These  two  principles  constitute  the  corner  stone  of  physical 
science,  and  must  be  learned  and  kept  in  mind  if  we  would 
understand  the  actions  of  our  bodies,  and  our  relations  to  the 
surrounding  parts  of  the  world  and  the  universe  in  which  we 
live  and  of  which  we  must  consider  ourselves  a  part. 

What  is  the  object  of  this  ceaseless  change  of  nutrition 
and  growth  ?  Is  it  simply  that  the  body  may  be  nourished  ? 
Do  we  live  to  eat,  or  do  we  eat  to  live  ?  And  what  is  it  to 
live  ?  Merely  to  be  an  animal,  even  the  most  highly  devel- 
oped on  this  earth  ? 

"  On  earth  there  is  nothing  great  but  man.  In  man  there 
is  nothing  great  but  Mind."  The  muscles  are  the  servants 
of  the  will.  These  servants  we  have  been  studying.  Let  us 
turn  to  the  study  of  the  Master  Tissue,  the  central  nervous 
system. 

READING.  —  See  Appendix. 


CHAPTER   VIII. 

THE    BRAIN. 

THE  muscles  are  the  executive  organs.  But  the  seat  of 
the  Will  is  the  brain. 

Let  us  study  its  structure  and  relations  in  order  to  come 
nearer  to  an  understanding  of  its  functions. 

Directions  for  preparing  the  Brain  of  a  Cat  or  Rab- 
bit. —  Directions  have  been  given  on  page  32  for  uncover- 
ing the  brain.  To  remove  the  brain,  it  will  be  necessary  to 
cut  through  the  tough  Dura  Mater  that  covers  it. 

,  Removing  this,  there  will  be  found  an  inner  covering,  the 
Pia  Mater,  a  membrane  richly  supplied  with  blood  tubes,  from 
which  the  brain  gets  its  nourishment.  After  the  dura  mater 
has  been  removed,  the  anterior  end  of  the  brain  may  be  gently 
lifted  with  the  handle  of  the  scalpel  and  the  under  surface 
studied,  following  the  directions  in  rinding  the  cranial  nerves. 

The  brain  may  be  studied  while  it  is  fresh,  but  it  is- more 
easily  handled  after  it  has  been  hardened.  Lay  the  brain 
in  weak  alcohol,  about  twenty-five  per  cent.  It  should  rest 
on  a  layer  of  cotton,  otherwise  it  may  be  very  much  flattened 
by  its  own  weight,  and  get  a  good  deal  out  of  shape.  Later 
transfer  it  to  fifty  per  cent  alcohol,  and  then  to  seventy-five 
per  cent,  or  use  a  solution  of  alcohol  and  formalin  as  fol- 
lows :  95  per  cent  alcohol,  60  parts  ;  2  per  cent  formol,  40 
parts.  The  liquid  need  not  be  changed  if  used  in  sufficient 
volume.  (See  Appendix  for  another  formula.)  When  it  is 
well  hardened,  it  may  be  sliced  with  a  sharp  scalpel  as  di- 
rected. 

The  Brain  of  the  Rabbit  (Alcoholic   Specimen).  —  The 

253 


254  CRANIAL   NERVES. 

brain  of  a  cat  or  dog  is  better,  being  larger.  Take  a  brain 
well  hardened,  and  review  the  parts  as  named  above.  It  is 
very  desirable  to  have  a  specimen  in  which  the  arteries  have 
been  injected. 

1.  Press  down  the  cerebellum,   to   see    the    deep  groove 
between  it  and  the  cerebrum.     The  thin  membrane  covering 
the  brain,  and  dipping  into  the  grooves,  is  the  Pia  Mater. 

2.  Press  down  the  spinal  bulb  (medulla  oblongata),  and 
tear  away  the  pia  mater  where  it  passes  from  the  cerebellum 
to  the  spinal   bulb.     Note,  between  the  bulb  and  the  cere- 
bellum, a  space  covered  by  a  thin  membrane.     Cut  through 
this  membrane;    the   cavity  is  the   Fourth   Ventricle   of   the 
brain.     Observe    the  two  ridges   bounding  the  sides   of   the 
fourth  ventricle.     At  the  point  of  their  divergence,  observe 
the  opening  of  the  Central  Canal  of  the  spinal  cord. 

3.  Gently  separate  the  cerebral  hemispheres,  and  note  the 
transverse  band  of  white  fibers  connecting  them. 

4.  Examine  the  under  surface  of  the  brain,  and  find  the 
roots  of  the  cranial  nerves. 

The  Cranial  Nerves.  —  1.  The  Olfactory  Lobes  (probably 
cut  or  broken  off)  extend  forward  from  the  fore  part  of  the 
cerebral  hemispheres. 

2.  Note  that  the  Optic  Nerves  join  each  other  before  reach- 
ing the  brain.     Only  the  first  and   second   pairs  of  cranial 
nerves  directly  enter  the  cerebrum. 

3.  Back  of  the  optic  nerves,  near  the  middle  line,  are  the 
third  pair  of  nerves. 

4.  The  fourth  pair  extend  up  on  each  side  into  the  groove 
between  the  cerebrum  and  the  cerebellum. 

5.  Back  of  these  are  the  larger  fifth  pair.     This  pair  sup- 
ply part  of  the  face,  and  send  branches  to  the  teeth.     It  is 
the  nerve  affected  in  neuralgia  of  the  face. 

6.  Back  of  and  inside  of  the  fifth  .pair  are  the  sixth  pair. 


BASE   OF  THE  HE  A  IN. 


255 


7.  The  nerves  of   the   seventh    pair  are   larger,   and  are 
farther  back  and  outward.     These  are  the  Facial  Nerves,  and 
control  the  muscles  of  the  face  and  the  facial  expression. 

8.  Close  to  the  seventh  are  the  eighth,  or  Auditory  Nerves. 


Optic,  2 

(sight) 


Eye 
Motor, 
3,4,6 


Hypoglossal, 
12  (Tongue 
Motor) 


I,  Olfactory 
(Smell) 


'  7,  Facial 
(Face 
Motion) 


9,  Glosso- 
pharyngeal 


II,  Spinal 
Accessory 


Fig.  78.     The  Base  of  the  Brain,  Showing  the  Origin  of  the  Cranial  Nerves. 

9.  The    ninth,    tenth,   and    eleventh    arise   close   together, 
farther  back  and  well  up  on  the  sides  of  the  Spinal  Bulb. 

10.  The  ninth  supplies  the  back  of  the  tongue  and  the  phar- 
ynx, and  is  called  the  Glosso-pharyngeal  Nerve. 


256  HEMISECTION  OF  BRAIN. 

11.  The  tenth  pair  pass  down  out  of  the  brain  cavity,  give 
off  branches  to  the  pharynx  and  larynx,  and  are  distributed  to 
the  heart,  lungs,  and   stomach;  hence  the  name  Pneumogas- 
tric  Nerves. 

12.  The  last  pair  of  cranial  nerves,  the  twelfth,  arise  near 
the   middle  line  of  the  spinal  bulb.     This  pair  supply  the 
muscles  of  the  tongue,  and  are  called  the  Hypoglossal  Nerves. 


Cerebrum 


Spinal  Bulb 


Fig.  79.     Vertical  Section  of  Brain. 

Draw  the  brain  as  seen  from  below,  showing  all  these  nerves. 

Separate  the  cerebral  hemispheres,  and  with  a  sharp  knife 
split  the  brain  lengthwise  in  the  middle  line.  Make  a  draw- 
ing of  the  inner  face  of  one  half.  Note  the  branched  appear- 
ance, the  Arbor  Vita,  of  the  cerebellum.  Trace  the  cavities  of 
the  brain. 


STRUCTURE   OF  BRAIN.  257 

Trace  the  blood  tubes  of  the  brain.  For  this  the  injected 
brain  of  a  cat  or  dog  should  be  used. 

Cut  and  examine  the  cross  sections  of  the  spinal  cord  after 
it  has  been  hardened  in  alcohol.  Compare  the  colors  of  the 
inside  of  the  brain  and  spinal  cord. 

It  will  be  observed  that  the  brain,  like  the  spinal  cord, 
consists  of  two  lateral  halves.  Cutting  sections  of  the  brain 
lengthwise  and  crosswise  shows  that  the  outer  part  is  made 
up  of  gray  matter  and  the  inner  part  of  white  matter.  The 
gray  matter  is  composed  of  cells  essentially  similar  to  those 
of  the  spinal  cord,  while  the  white 
matter  of  the  inner  part  is  composed 
of  white  fibers  like  those  of  the  outer 
part  of  the  spinal  cord,  or  like  the 
nerves. 

In  comparing  the  brain  of  the  rab- 
bit and  the  cat,  that  of  the  rabbit  is 
found  to  have  fewer  convolutions,  and  Fig.  so. 

is    nearly    smooth.       In    general,    the       Pyramidal  Nerve  Ceils,  found 

t  principally  in   the   Gray 

lower    animals    have    fewer    coiivolu-  Matter  of  the  Brain. 

tioiis,  and  the  lower  races  of  man- 
kind have  smoother  brains  than  the  higher  races.  In  the 
earlier  stages  of  development  man's  brain  is  smoother;  but 
with  growth  the  convolutions  appear,  and  increase  in  number 
with  the  growth  of  the  brain.  As  we  know  that  intelligent 
action  depends  on  the  gray  matter  of  the  surface  of  the  brain, 
we  infer  that  to  accommodate  its  increase  in  the  brain-case  it 
is  thrown  into  folds,  as  the  surface  of  the  lining  of  the  intes- 
tines is  increased  by  folds,  villi,  etc. 

The  gray  matter  of  the  convolutions  of  the  adult  human 
brain  is  about  one-fifth  of  an  inch  thick,  the  larger  part  of 
the  brain  consisting  of  the  white  matter.  Sections  will  show 
that  there  are  several  masses  of  gray  matter  in  the  brain 


258 


CRANIAL   NERVES. 


Gray   Matter 


Cerebrum 


Ganglia 


Cerebellum 


deeper  than  the  convolutions.  These  are  the  Ganglia  of  the 
brain.  The  white  fibers  inside  the  brain  connect  the  gray 
matter  of  the  convolutions  and  these  ganglia  with  all  parts  of 
the  body  through  the  spinal  cord. 

The  brain  consists  of  nerve-cells  and  nerve  fibers,  bound 
together  and  supported  by  a  form  of  connective  tissue  called 

Neuroglia, 

It  will  be 
found  extremely 
helpful  to  have  a 
set  of  models  of 
the  human  brain. 
The  parts  are  es- 
sentially the  same 
as  in  the  cat. 
Examine  the  base 
of  the  brain  in 
such  model,  and 
review  the  cra- 
nial nerves. 

The  Functions  of  the  Cranial  Nerves.  —  1.    The  first 
pair  of  cranial  nerves  are  the  Olfactory,  or  nerves  of  smell. 

2.  The  Optic  Nerves,  the  nerves  of  sight. 

3.  The  third  pair  control  muscles  of  the  eyeballs. 

4.  The  fourth  pair  control  muscles  of  the  eyeballs, 

5.  The  fifth  are  the  nerves  of  sensation  for  most  of  the 
head  and  face,  including  the  teeth.     The  fifth  pair  of  nerves 
are  like  the  spinal  nerves  in  having  two  roots,  a  motor  and  a 
sensor  root.     Some  of  the  fibers  run  to  the  muscles  of  masti- 
cation.    One  branch  of  the  fifth  nerve  is  distributed  to  the 
fore  part  of  the  tongue,  and  gives  the  sense  of  taste.     It  is 
called  the  Gustatory  Nerve,  or  the  gustatory  branch  of  the  fifth 
nerve. 


Fig.  81.     Diagram  of  the  Brain,  Showing  the  Spinal 
Cord,  Ganglia,  and  Course  of  the  Fibers^ 


FUNCTIONS   OF  CEREBRUM.  259 

6.  The  sixth  pair  control  muscles  of  the  eyeballs. 

7.  The   seventh  or  Facial  Nerve  is  the  nerve  controlling 
the  expression  in  the  face  as  it  is  distributed  to  the  facial 
muscles. 

8.  The  eighth  are  the  Auditory,  or  nerves  of  hearing. 

9.  The  ninth  are  the  Glosso-pharyngeal,  and  give  the  sense 
of  taste  from  the  base  of  the  tongue. 

10.  The  tenth,  the  vagi  or  Pneumogastric  Nerves,   extend 
not  only  to  the  lungs  and  stomach  as  the  name  indicates,  but 
also  send  fibers  to  the  heart,  gullet,  larynx,  etc. 

11.  The  eleventh  pair  arise  outside  of  the  cranial  cavity, 
enter,  and  pass  out  again,  to  supply  certain  muscles  of  the 
neck  and  shoulders. 

12.  The  twelfth  pair  control  the  muscles  of  the  tongue. 
The    Cerebrum    and    its    Functions.  —  If  the  cerebral 

hemispheres  are  removed  from  a  frog,  he  will  sit  up  about  as 
before,  but  seems  to  pay  little  attention  to  what  is  going  on 
around  him.  If  placed  on  his  back,  he  will  turn  over  and  sit  up. 
If  pinched,  he  may  jump  away,  and  may  show  that  he  can  see 
by  avoiding  anything  that  may  come  in  his  way.  If  placed  in 
the  water  he  will  swim,  and  if  he  swims  against  anything  that 
he  can  climb  upon,  will  do  so  and  remain  quiet.  If  placed  on 
a  board,  and  the  board  be  slowly  tilted,  he  will  move  along 
and  keep  his  equilibrium,  climbing  over  the  end  of  the  board 
if  necessary  to  keep  his  balance.  If  left  alone,  he  will  not 
move;  and  will  die  in  his  tracks,  though  he  will  eat  food  if 
it  is  put  in  his  mouth.  He  seems  to  have  lost  the  power  of 
Willing  to  do  anything,  or  what  we  call  the  power  of  Volition. 
He  originates  no  action. 

A  pigeon  with  its  cerebrum  removed  acts  in  about  the 
same  way.  It  remains  quiet,  stupid,  paying  no  attention  to 
ordinary  events.  A  sudden  loud  noise  may  cause  it  to  start. 
If  its  tail  be  pulled,  it  moves  forward  to  regain  its  balance. 


260 


BRAIN  AND   SENSE-ORGANS. 


If  thrown  in  the  air,  it  flies  for  a  distance.  It  swallows  food 
placed  in  its  mouth,  but  would  starve  surrounded  by  food. 
Placed  on  its  back  it  will  right  itself,  but  it  does  not  show  the 
usual  degree  of  Intelligence  and  Will-power. 

"Experimentally,  we  learn  that  after  the  removal  of  the 
cortex  (gray  matter)  an  intelligent  animal  is  reduced  to  the 


Face  Sensory ..._!V 
Face  Motions f^ 

Taste- 


/-.Spinal  Cord 

1st  Spinal  Nerve 
2d  Spinal  Nerve 


Fig.  82.     Diagram  of  the  Cranial  Nerves  and  Sense  Organs. 

state  of  a  non-intelligent  automaton,  responding  indeed  to 
stimuli,  internal  as  well  as  external,  but  failing  to  interpret 
the  significance  of  present  events  in  accordance  with  bygone 
experience.  A  brainless  dog  is  stupid ;  he  may  see  a  bone  in 
front  of  his  eyes  without  showing  signs  that  he  knows  the 


CEREB  RAL    COR  TEX  —  SENS  A  TION.  26 1 

meaning  of  a  bone,  or  the  use  to  which  it  may  be  put ;  he  may 
hear  the  crack  of  a  whip,  but  he  no  longer  shows  signs  of 
fear,  for  he  does  not  remember  its  sting ;  his  former  purpose- 
ful behavior  has  entirely  disappeared ;  in  short,  he  has  lost 
memory  and  judgment."  —  WALLER. 

In  an  earlier  chapter  we  learned  that  the  cortex  (gray  mat- 
ter of  the  outside  of  the  brain)  is  the  central  organ  of  intelli- 
gent sensation  and  motion.  The  functions  of  Volition,  of 
Consciousness,  of  Intelligence,  seem  to  reside  in,  or  rather  to 
depend  upon  the  activities  of,  the  cells  of  the  gray  matter  of 
the  convolutions  of  the  cerebrum.  This  we  have  learned  from 
experiments  on  the  lower  animals,  and  from  accidents  and  dis- 
ease in  the  case  of  man.  All  sensation  seems  to  be  in  the 
gray  matter  of  the  convolutions  of  the  cerebrum,  and  yet  it  is 
itself  insensible ;  it  may  be  cut  and  cause  no  sensation.  But 
when  the  nerve  impulses  from  the  various  parts  of  the  body 
reach  the  gray  matter  of  the  cerebrum,  they  rouse  the  cells 
here  to  an  activity  that  gives  us  what  we  call  sensation.  It  is 
never  a  sensation  until  it  reaches  this  part,  and -is  properly 
interpreted. 

While  each  hemisphere  mainly  controls  the  muscles  of  the 
opposite  half  of  the  body,  it  also,  in  part,  has  control  of  its 
own  side.  Paralysis  of  one  side  (hemiplegia)  is  due  to  injury 
of  the  opposite  cerebral  hemisphere. 

Much  has  been  learned  of  late  years  as  to  the  location  of 
special  functions  in  the  brain.  Many  of  the  motor  centers 
have  been  determined  in  the  following  manner :  In  some  of  the 
lower  animals  the  brain  has  been  exposed,  and  on  stimulat- 
ing certain  portions  with  an  electric  current,  the  movements 
that  followed  were  noted.  In  apes,  "particular  movements 
of  the  arm,  forearm,  hand,  and  thumb  can  be  produced  by 
excitation  of  particular  spots,  almost  as  regularly  as  definite 
notes  can  be  sounded  on  a  piano  by  touching  particular  keys." 


262 


LOCATION  OF  BRAIN  FUNCTIONS. 


In  the  case  of  man  we  infer  that  there  is  a  similar  location, 
and  many  cases  of  accident  and  disease  have  helped  in  this 
work  of  locating  the  functions.  But  these  areas  are  not 
sharply  denned. 

The  "  speech  center  "  is  in  the  left  hemisphere ;  the  right 
eye  and  ear,  which  connect  with  the  left  brain,  are  better  de- 


CENTRAL   FISSUfi 

MOTOR  AREA  /' 


FISSURE  OF  SILVIUS 


Fig.  83.     Location  of  Brain  Functions. 

veloped  than  the  left,  and  in  general  the  left  hemisphere 
seems  superior  (in  right-handed  persons)  to  the  right. 

It  is  not  so  easy  to  locate  the  centers  of  sensation  as  those 
for  motion.  For  we  can  see  the  resulting  motion,  but  a  sen- 
sation can  only  be  felt  by  the  individual  in  whom  it  occurs. 
Still,  some  of  the  sensation  centers  have  been  located,  and  it 


FUNCTION  OF  CEREBELLUM.  26*3 

is  likely  that  in  time  we  shall  know  much  more  on  this 
subject. 

The  accompanying  diagram  shows  some  of  these  centers. 

The  Functions  of  the  Cerebellum.  — -  The  cerebellum  is 
the  center  for  regulating  the  actions  of  the  skeletal  muscles. 
When  we  walk  or  run,  or  even  stand  still,  a  number  of  mus- 
cles must  act,  and  act  in  concert.  The  nerve  impulses  origi- 
nate in  the  cerebrum;  but  the  cerebellum  is  the  center  for 
harmonizing  the  action  of  these  various  muscles,  or  Coordi- 
nating them.  When  the  cerebellum  has  been  removed  from 
a  pigeon  the  bird  nutters,  and,  while  possessing  the  power  to 
move,  does  not  seem  capable  of  any  regular  and  orderly 
movement.  There  is  no  loss  of  intelligence,  no  paralysis. 
Of  course,  in  this  experiment  there  is  great  disturbance  of 
the  system,  and  perhaps  too  much  is  inferred  from  it. 

The  Spinal  Bulb.  —  The  Spinal  Bulb  (medulla  oblongata) 
is  the  connection  between  the  spinal  cord  and  the  brain.  The 
bulb  may  be  said  to  be  that  part  of  the  spinal  cord  which  is 
within  the  cranium.  It  is  enlarged,  hence  its  name,  Spinal 
Bulb.  From  it  arise  all  the  cranial  nerves  except  the  first 
five  pairs.  The  spinal  bulb  is  also  the  center  for  the  control 
of  many  processes.  It  is  the  center  for  the  control  of  respi- 
ration, of  circulation,  of  deglutition,  and  perhaps  for  many 
other  processes. 

Blood  Supply  of  the  Brain.  —  Brain  Work  and  Brain 
Rest.  —  During  the  period  when  the  brain  is  more  active,  it 
receives  a  larger  supply  of  blood.  During  sleep  it  is  paler. 
Sleep  is  not  merely  rest  for  the  body ;  it  should  be  complete 
rest  for  the  brain.  In  so  far  as  there  are  dreams,  it  would 
seem  to  indicate  a  partial  activity ;  that  is,  incomplete  rest. 
The  brain-worker  especially  needs  plenty  of  sleep  ;  excellent 
authorities  say  at  least  eight  or  nine  hours.  The  brain,  like 
the  muscles,  needs  exercise ;  and  it  also  needs  regular  periods 


264  BRAIN   WORK — BRAIN  REST. 

of  rest.  If  a  nerve-cell  is  not  kept  active  by  the  passage 
of  nerve  impulses  through  it,  it  usually  atrophies,  and  may 
degenerate. 

Intense  brain  work,  without  sufficient  sleep,  is  likely  to 
lead  to  sleeplessness,  as  when  one  has  some  subject  of  special 
study  in  hand  and  either  will  not  or  cannot  throw  it  off. 
Perhaps  inventors  are  as  prone  to  this  sort  of  trouble  as  any 
one  class  of  men.  Keeping  the  blood  continually  in  the 
brain,  or  in  any  organ,  is  likely  to  lead  to  a  permanent  con- 
gestion or  inflammation  that  may  cause  serious,  if  not  fatal, 
results.  It  is  stated  that  brain-workers  need  more  sleep  than 
those  who  work  chiefly  with  the  muscles.  Fatigue  of  the 
voluntary  muscles  is  much  more  a  matter  of  nervous  than  of 
muscular  origin.  When  one  is  completely  "  tired  out,"  as  he 
would  say,  if  his  mind  can  be  aroused,  as  by  some  excite- 
ment, he  will  be  found  able  to  expend  a  good  deal  more  mus- 
cular energy.  So,  too,  many  persons  of  slight  muscular  build, 
but  of  great  "  will-power,"  are  able  to  do  more  work  with  the 
muscles  than  others  with  larger  muscles  and  less  will. 

But  the  brain-worker  should  not  only  be  able  to  sleep 
regularly  and  long  enough,  he  ought  to  be  able  to  throw  off 
his  mind  any  subject,  and  take  rest  while  he  is  awake.  If 
one  allows  himself  to  think  about  mental  work  while  eating, 
the  process  of  digestion  will  not  go  on  well. 

The  student  should  acquire  the  power,  and  cultivate  the 
habit,  of  having,  so  far  as  possible,  regular  hours  for  work, 
and  of  completely  throwing  aside  his  work  and  worry  at 
stated  times.  In  seeking  recreation  it  is  well  to  choose 
that  which  will  necessitate  giving  the  attention  to  something 
entirely  different  from  the  daily  work.  For  this  reason  chess 
may  be  no  real  recreation  for  the  student,  while  a  game  of 
tennis,  boxing,  or  other  competitive  exercise  is  likely  to  ac- 
complish this  very  desirable  object.  A  walk  may  put  the 


FAINTING.  265 

muscles  into  play ;  but  if  the  mind  is  still  intent  upon  the 
line  of  work  maintained  throughout  the  day,  the  exercise  may 
prove  of  little  benefit.  He  may  return  more  tired  than  when 
he  set  out.  The  exhilaration  of  horseback  riding  may  prove 
far  better,  though  perhaps  involving  much  less  musculai 
exertion. 

During  fatigue  the  cell-bodies  are  found  to  decrease  in 
size,  but  there  is  no  discernible  change  in  nerve  fibers  as  a 
result  of  fatigue. 

It  is  worthy  of  note  that  in  fasting  the  nervous  tissue  is 
less  reduced  than  any  other  tissue,  being  scarcely  diminished 
by  complete  starvation. 

Blood  is  supplied  to  the  brain  through  four  arteries,  —  the 
right  and  left  Internal  Carotid  arteries,  and  the  right  and  left 
Vertebral  arteries.  These  arteries  are  so  connected  by  cross 
branches  that  if  any  three  of  them  should  be  compressed, 
or  the  blood-flow  in  them  otherwise  stopped,  the  fourth  would 
still  be  able  to  give  the  brain  blood  enough  for  its  work. 

If  the  supply  of  blood  to  the  brain  is  shut  off,  uncon- 
sciousness quickly  follows.  In  the  ordinary  faint  the  blood 
supply  has  been  reduced,  owing  to  the  diminution  of  the 
blood  pressure  or  heart's  force.  It  may  be  due  to  inhibition 
of  the  heart  from  some  emotion,  or  bad  odor,  as  in  a  close 
room ;  severe  pain  may  be  the  cause;  a  blow  over  the  pit  of 
the  stomach  may  stop  the  heart  by  reflex  action.  Fresh  air 
should  be  supplied,  and  the  body  laid  flat  on  the  back.  This 
position  makes  it  easier  for  the  blood  to  reach  the  brain  and 
restore  consciousness.  Smelling  salts  (or  ammonia)  may  stim- 
ulate respiration  and  circulation.  Sprinkling  a  little  cold 
water  on  the  face  may  have  the  same  effect,  but  it  is  not  ne- 
cessary to  pour  a  large  quantity  of  water  over  the  person. 
Rubbing  the  limbs  toward  the  heart  promotes  the  flow  of 
blood,  and  tends  to  start  the  heart  to  activity. 


266  NERVE  STIMULI. 

Apoplexy  is  caused  by  rupture  of  a  blood  tube  and  the 
formation  of  a  clot  that  presses  on  the  brain.  In  meningitis 
there  is  inflammation  of  the  membranes  immediately  sur- 
rounding the  brain  or  spinal  cord  or  both. 

Between  the  coats  surrounding  the  brain  and  spinal  cord 
there  is  a  layer  of  liquid,  comparable  .to  that  around  the  heart 
or  lungs.  When  an  undue  amount  of  blood  is  sent  to  the 
brain  it  is  supposed  that  part  of  the  cerebro-spinal  fluid  is 
pressed  out  into  the  spinal  cavity,  thus  relieving  the  pressure 
in  the  brain  cavity. 

The  gray  matter  is  physiologically  more  active  than  the 
white,  and  in  keeping  with  this  is  the  fact  that  the  capillary 
network  is  closer  in  the  gray  matter  than  in  the  white.  This 
is  true  of  the  spinal  cord  as  well  as  of  the  brain. 


GENERAL    CONSIDERATIONS    CONCERNING    THE     NERVOUS 

SYSTEM. 

Nerve  Stimuli.  —  Natural  nerve  impulses  that  run  out- 
ward are  ordinarily  started  by  the  action  of  some  nerve  cell 
or  cells,  as  from  the  gray  matter  of  the  brain  or  of  the  spinal 
cord. 

Nerve  impulses  coming  inward  may  be  started  in  several 
ways.  Ordinarily  by  some  one  of  a  few  forces  that  are  capa- 
ble of  affecting  the  nerve  endings. 

Mechanical  force,  as  pressure,  acts  on  the  nerve  endings  of 
the  skin,  and  starts  nerve  impulses  which  are  carried  to  the 
brain  and  rouse  certain  cells  to  activity,  and  give  us  the  sen- 
sation of  touch.  The  vibrations  known  as  light  excite  the 
special  nerve  endings  in  the  retina,*  but  affect  no  other  nerve 
endings.  Sound  is  appreciated  only  by  the  endings  of  the 
auditory  nerve.  Certain  gases  or  fine  particles  affect  the 
olfactory  nerve  endings,  and  certain  substances  may  give 


GENERAL   SENSATIONS.  267 

the  sense  of  taste  by  acting  on  the  ends  of  nerves  in  the 
mouth.  Different  nerve  endings  then,  are  adapted  to  re- 
ceiving impressions  from  the  action  of  different  forces. 

Nerve  endings  in  different  parts  of  the  body  may  be  affected 
by  the  blood  and  the  lymph,  and  give  us  sensations  of  comfort 
or  discomfort,  restlessness,  fatigue,  faintness,  etc.  These  are 
called  General  Sensations.  They  are  probably  due  to  the  con- 
dition of  the  blood,  or  to  the  condition  of  nutrition  of  the 
.various  parts  of  the  body.  Thus  after  muscular  exercise  the 
muscles  are  acid  in  their  reaction,  while  they  are  alkaline  after 
resting ;  after  exercise  carbon  dioxid  accumulates  in  them  to 
a  certain  extent.  Hunger  and  thirst  come  on  after  abstinence 
from  food  and  drink,  or  after  work  exhausting  the  tissues. 
The  presence  of  the  various  waste  products,  or  the  condition 
of  the  cells  as  the  result  of  their  activity,  acting  through  the 
nerve  endings,  in  the  tissues,  keep  the  nerve  centers  informed 
as  to  the  condition  of  the  parts  of  the  body.  If  these  condi- 
tions are  extreme  we  may  have  definable  sensations  ;  but  ordi- 
narily the  sensations  are  of  an  undefinable  sort,  which  we 
designate  as  "  general  sensations." 

In  experiment  electricity  is  usually  the  best  stimulus ; 
mechanical  stimuli,  as  "ufed  in  the  experiments  with  the 
muscle-nerve  preparation  from  the  frog,  by  cutting  or  pinch- 
ing the  nerve,  may  be  employed ;  hea"t,  as  in  touching  the 
nerve  with  a  hot  wire,  or  holding  a  hot  wire  near  the  nerve, 
may  be  used  as  a  stimulus ;  chemical  stimuli,  as  acids,  strong 
salt  solution,  etc.,  may  also  be  used. 

It  is  to  be  noted  that  while  special  stimuli  act  on  specially 
modified  nerve  endings,  all  nerve  fibers  are  essentially  alike ; 
and  the  nerve  impulse,  however  started,  is  probably  the  same 
kind  of  force.  For  instance,  cutting  the  optic  nerve,  or  severe 
shock,  as  a  blow  on  the  head,  causes  a  sensation  of  light  not 
quite  so  definite,  but  essentially  the  same  as  though  light  had 


268  REACTION  TIME. 

acted  on  the  retina,  and  thus  started  the  nerve  impulse,  instead 
of  a  mechanical  stimulus  acting  011  the  nerve  libers  between 
the  retina  and  the  brain. 

If  we  apply  a  stimulus  of  a  given  intensity,  as  of  an  elec- 
tric current,  whose  intensity  can  be  measured,  it  causes  a  sen- 
sation of  a  certain  degree.  Doubling  the  stimulus,  or  increasing 
it  by  a  definite  amount,  does  not  increase  the  intensity  of  the 
sensation  to  the  same  degree.  The  sensations  do  not  increase 
at  the  same  rate  as  the  stimuli.  To  increase  the  sensations 
arithmetically,  the  stimuli  must  increase  geometrically. 

"  Reaction  time  "  is  the  time  between  the  application  of  a 
stimulus  and  the  signal  given  as  a  response  to  show  that  the 
stimulus  has  been  "  felt."  Thus  a  blindfolded  person  gives  a 
signal  as  soon  as  he  is  touched.  This  interval  between  the 
stimulus  and  response  varies  with  the  individual,  mode  of 
stimulation,  health,  attention,  etc.  It  is  from  one-tenth  to 
one-fifth  of  a  second ;  is  shortest  for  touch ;  longer  for  sight 
than  for  hearing.  The  total  reaction  time  is  occupied  by  (1) 
the  time  of  conducting  the  nerve  impulse  to  the  brain,  (2)  the 
time  occupied  in  the  cerebral  cortex  in  the  perception  of  the 
sensation  and  the  formation  of  the  volition,  (3)  the  time  of 
conducting  the  motor  impulse  and  giving  the  signal.  The 
greater  part  is  in  the  middle  interval ;  i.e.,  the  central  elab- 
oration, during  which  the  entering  impression  gives  rise  to  an 
outgoing  impulse. 

In  a  previous  diagram  of  reflex  action,  a  single  cell  was 
represented  as  receiving  the  afferent  impulse  and  sending  out 
an  efferent  one.  It  is  more  probable  that  at  least  two  cells 
are  concerned  in  such  an  act,  one  receiving  the  incoming  im- 
pulse, and  influencing,  by  means  of  fine  connecting  branches, 
a  second  cell  which  sends  out  the  motor  impulse,  as  shown  in 
Fig.  84. 

We  have  seen  that  the  brain  functions  are  more  or  less 


REFLEX  ACTION.  269 

localized.  We  also  know  that  the  cortex  receives  impressions 
through  the  channels  of  the  different  sense  organs,  and  we  can 
respond  through  various  channels,  —  speech,  writing,  facial 
expression,  etc.  We  would  therefore  expect,  theoretically, 
that  the  various  parts  of  the  cortex  of  the  brain  are  connected. 
As  a  matter  of  fact,  we  find  anatomically  that  this  is  the  case. 
Not  only  are  the  cells  of  the  gray  matter  connected  with  the 


Nerve  Cells  Connected  by  Interlacing  Nerve  Network 


Afferent  Nerve  Fiber  41  YY  Efferent  Netve  Fiber 


Sensory 
Epithelium 


Fig.  84.     Diagram  of  Reflex  Action. 


various  parts  of  the  body,  but  cells  of  different  parts  of  the 
cortex  are  in  communication  with  each  other  by  what  are 
called  "association  fibers."  Thus  a  sensation  roused  in  one 
part  of  the  brain  gives  rise  to  the  sending  out  of  an  impulse 
from  another  part  of  the  brain  to  produce  the  response. 

The  Nature  of  Sensation.  —  Of  the  real  nature  of  sensa- 
tion we  know  but  little.  Like  consciousness,  we  call  it  a  con- 
dition of  the  gray  matter  of  the  cerebral  convolutions.  Perhaps 


270 


A SSOCIA  TION  FIBERS. 


Writing 


Speech 


the  most  practical  definition  of  sensation  that  we  can  give  is 
that  it  is  the  interpretation  that  the  cells  of  the  gray  matter  of 
the  brain  give  to  the  nerve  impulses  that  come  from  without. 

This  will  apply  to 
ordinary  sensa- 
tions. But  sensa- 
tions may  be  sub- 
jective; that 
is,  they  may 
exist  without 
any  corresponding 
external  exciting 
cause.  For  some 
unexplained  reason 
the  cells  of  the 
brain  are  active ; 
and  their  activity, 
however  caused, 
constitutes  what  we 
call  a  sensation. 
Certain  drugs,  such 
as  hashish,  may 
excite  an  unusual 
degree  of  cerebral 
activity.  Here  the 

Fig.  85.     Connection  of  Brain  Centers  by  Association  a  C  t  i  O  H     is     TOUSed 

Fibers.     (After  Landois  &  Stirling.) 


(The  dotted  lines  from  the  hand,  mouth,  and  eye 
represent  afferent  fibers  from  the  skin,  muscles,  and 
joints  of  the  hand,  lips,  orbit,  etc.) 


through  afferent 
nerves,  but  through 
unusual  channels ; 
that  is,  the  subject 

sees,  but  not  through  the  nerves  of  sight.  Many  Hallucina- 
tions are  explainable  to  a  certain  degree ;  others  we  may  not 
account  for. 


DliEAMS.  271 

Dreams,  due  to  more  or  less  perfect  brain  activity,  are 
often  traceable  to  nerve  impulses  brought  from  the  digestive^ 
tract,  from  the  respiratory  organs,  from  the  skin  (heat  and 
cold  and  pressure),  from  any  internal  organ,  according  to  the 
condition  of  the  blood,  pressure,  sound,  etc.  It  seems  to  be 
well  settled  that  dreams  seeming  to  cover  long  periods  of 
time  are  really  gone  through  with  in  a  very  short  space  of 
time,  just  as  sometimes  during  waking  hours  thoughts  fly 
through  the  mind  in  countless  numbers  and  with  incredible 
swiftness. 

Do  we  have  dreams  when  we  recall  none  ?  Without 
attempting  to  answer  this  question,  it  is  well  to  note  that  the 
brain  undoubtedly  is  constantly  receiving  nerve  currents  to 
which  it  pays  no  heed,  or  at  least  of  which  we  are  not  con- 
scious. For  instance,  our  clothing  is  touching  nearly  the 
whole  of  the  surface  of  our  bodies,  and,  plainly,  the  surfaces 
thus  touched  are  affected.  Undoubtedly  currents  go  to  the 
brain ;  but,  as  they  are  of  no  significance  in  ordinary  circum- 
stances, we  learn  to  disregard  them.  If  a  savage  were  sud- 
denly clothed  as  fully  as  we  are,  he  would,  for  a  long  time, 
be  continually  conscious  of  the  fact. 

We  ordinarily  disregard  many  forces  that  are  operating 
upon  us ;  many  sounds  are  ignored,  many  objects  we  do  not 
see  as  they  really  appear  to  us.  For  instance,  if  one  sits 
behind  a  bald-headed  man  in  a  church,  in  looking  over  the 
top  of  his  head  at  the  choir,  the  top  of  his  head  appears 
peaked,  because  while  the  eyes  are  focused  on  the  more  dis- 
tant object,  the  images  of  the  man's  head,  as  seen  by  the  two 
eyes,  do  not  coincide,  but  overlap  each  other ;  and  what  is 
seen  is  the  part  where  the  two  images  overlap,  which  forms 
a  pointed  arch.  We  may  be  sure  this  is  what  we  always  see, 
but  seldom  notice.  And  this  is  only  a  sample  of  the  many  ap- 
pearances and  sensations  that  we  have  learned  to  ignore.  To 


272  RELATIVE  NATURE  OF  SENSATION. 

an  infant  they  are  just  as  apparent  as  the  phenomena  to  which 
.we,  in  later  life,  learn  to  attach  meaning  and  significance. 

The  Relative  Nature  of  Sensations.  —  If  one  hand  be 
held  in  a  basin  of  hot  water  and  the  other  in  a  basin  of  cold 
water,  and  then  the  two  be  suddenly  plunged  into  a  third 
basin  containing  tepid  water,  a  sensation  of  cold  will  be  re- 
ceived from  the  hand  that  was  in  the  hot  water,  while  the 
hand  from  the  cold  water  will  feel  heat.  Sensations  depend 
on  comparison  and  contrast.  After  listening  to  low  sounds,  a 
sudden  loud  noise  is  painful ;  and  after  hearing  loud  noises, 
it  is  difficult  to  detect  slight  sounds.  We  hardly  notice  the 
gradual  fading  of  the  light  at  sunset.  And  the  nose  does  not 
usually  detect  the  slow  fouling  of  the  air  in  a  room  ;  but  let 
one  come  in  from  the  fresh  outside  air,  and  the  contrast  is 
striking.  A  constant  current  of  electricity  usually  causes  a 
muscular  contraction  at  the  time  the  current  enters  the  muscle 
and  at  the  time  when  the  current  is  stopped,  that  is,  at  the 
"  making "  and  the  " breaking"  of  the  current;  but  the  muscle 
ordinarily  remains  inactive  while  the  current  is  passing.  The 
Interrupted  Current,  or  Induction  Current,  is  therefore  com- 
monly employed  as  a  stimulus  in  physiological  experiment.  A 
sudden  change  seems  to  be  requisite  for  producing  the  nerve 
impulse  necessary  to  rouse  a  sensation  in  ordinary  circum- 
stances. Pressure  may  be  applied  so  gradually  that  we  fail 
to  notice  it.  The  art  of  the  pickpocket,  of  the  ventriloquist, 
of  the  sleight-of-hand  performer,  depends  largely  on  this  fact. 
Attention  is  called  to  something  else,  and  the  work  is  either 
quickly  done  when  attention  is  completely  absorbed  on  some- 
thing else,  or  the  act  is  so  gradual  that  no  sudden  change  is 
noted.  In  smelling  it  is  often  necessary  to  sniff ;  the  sudden 
rush  of  particles  of  air  bearing  the  odorous  particles  against 
the  surface  bearing  the  nerve  endings  seems  to  be  necessary. 
Perhaps  this  is  why  the  fish  has  two  nasal  openings  on  each 


FUSED   SENSATIONS.  273 

side;  namely,  that  there  may  be  a  decided  current  of  water 
over  the  nerve  endings ;  for  it  is  found  that  if  the  human  nos- 
trils be  filled  with  rose-water  no  odor  is  perceived. 

In  what  is  called  Aristotle's  experiment,  the  experimenter 
crosses  the  first  and  second  finger,  and  feels  an  object  with 
the  fingers  thus  crossed  and  eyes  shut.  If  a  marble  be  rolled 
about  by  the  two  fingers  thus  crossed,  it  seems  to  be  two. 
Here  we  use  Judgment  with  the  sensation.  Ordinarily  we 
could  not  feel  one  simple  solid  object  with  the  outside  of  the 
first  and  the  inside  of  the  second  finger  at  the  same  time. 
This  illustrates  how  we  are  constantly  using  our  judgment  in 
interpreting  our  sensations.  We  see  few  things  as  they  are 
in  themselves.  We  see  nearly  everything  in  the  light  of  past 
experiences. 

We  have  noted  the  lingering  effects  of  sensations,  how 
sights  and  sounds  linger  and  are  fused  one  with  the  other, 
so  we  get  continuous  light  from  a  series  of  flashes  if  they 
follow  each  other  in  sufficiently  rapid  succession,  and  con- 
tinuous sound  from  a  series  of  sounds  that  would  be  heard 
separately  if  they  are  more  than  about  a  sixteenth  of  a  second 
apart.  So  with  touch,  if  the  finger  be  held  against  the  teeth 
of  a  revolving  wheel,  if  the  wheel  revolve  slowly,  the  touch 
of  each  tooth  may  be  felt,  but  when  it  whirls  more  rapidly 
the  sensation  becomes  that  of  continuous  pressure.  And  it 
is  of  vastly  greater  significance  that  the  cells  whose  activity 
gives  consciousness  —  that  a  more  permanent  effect  still  is 
produced ;  so  that  we  may  recall,  in  the  act  called  Imagina- 
tion, the  sensation  that  was  originally  caused  by  the  action  of 
some  external  object,  through  the  nerve-ending  and  the  nerve, 
upon  the  nerve-cells  in  the  brain.  Experience  and  experiment 
both  go  to  show  that  probably  nothing  is  wholly  forgotten. 
Whatever  acts  upon  a  cell  of  nervous  matter  makes  its  mark. 
It  may  become  dim,  but  it  is  never  completely  obliterated. 


274  EFFECTS   OF  ALCOHOL. 

The  testimony  of  persons  rescued  from  drowning,  and  other 
similar  experiences,  goes  to  show  that  the  record  was  yet  in 
the  mind.  We  may  fail  to  Recollect,  but  we  ever  remember. 

EFFECTS    OF    ALCOHOL    ON    THE    NERVOUS    SYSTEM. 
[Treatise  on  Hygiene,  STEVENSON  and  MURPHY.] 

"  The  physiological  effects  of  alcohol  which  have  been  con- 
sidered are  quite  subsidiary  to  its  effects  on  the  central  nervous 
system,  as  there  is  no  doubt  that  it  is  for  this  effect  on  the 
brain  that  alcoholic  beverages  are  so  universally  taken  by  man- 
kind. The  first  effect  that  alcohol  has  on  the  brain  is  that 
of  a  stimulant,  and  it  probably  acts  as  such  in  two  ways ; 
namely,  by  increasing  the  circulation  of  blood  through  the 
brain,  which  is  thus  roused  to  greater  vigor,  and  by  directly 
stimulating  the  nerve-cells  of  the  nerve  centers.  This  stimu- 
lating effect  is  observed  chiefly  after  medium  or  dietetic  doses ; 
and  its  result  is  seen  in  many  individuals  by  an  increase  of 
mental  and  bodily  activity,  and  of  acuteness  of  perception 
by  the  special  senses.  This  beneficial  physiological  effect  is, 
however,  soon  replaced  by  poisonous  symptoms  if  the  dietetic 
doses  are  too  often  repeated,  or  a  large  quantity  of  alcohol 
is  taken  at  once ;  for  alcohol  then  becomes  a  depressant  and 
paralyzer  of  the  central  nervous  system,  and  symptoms  of  in- 
toxication appear.  This  depressant  effect  is,  as  Brunton  points 
out,  one  of  progressive  paralysis.  The  higher  centers  of  the 
brain  are  first  affected,  then  the  lower.  The  perceptive  cen- 
ters are  paralyzed,  so  that  correct  judgment  is  no  longer  pos- 
sible, while  the  emotions  are  uncontrolled  and  thrown  out 
of  working  gear,  fits  of  boisterous  hilarity  and  of  emotional 
depression  being  common  symptoms.  Speech  becomes  disor- 
dered, and  symptoms  of  incoordination,  due  probably  to  an 
effect  on  the  cerebellum,  appear.  The  respiratory  center  in 


EFFECTS   OF  ALCOHOL.  275 

the  medulla  then  becomes  affected  ;  and  at  this  stage  there  is 
coma  with  stertorous  breathing,  while  the  action  of  the  heart 
still  continues,  even  after  respiration  has  stopped.  There  can 
be  no  question  that  alcohol  taken  in  sufficient  quantities  to 
depress  the  higher  centers  of  the  brain  does  an  infinite  amount 
of  harm." 

Dr.  Crothers,  author  of  Diseases  of  Inebriety,  says,  "  I  have 
often  been  made  impatient  in  listening  to  the  lecturer  pre- 
senting the  '  scientific  aspects  of  the  alcohol  question '  to  an 
audience,  to  see  him  illustrate  extensively  with  charts,  and 
spend  hours  to  show  the  effects  of  alcohol  upon  the  coats  of 
the  stomach,  and  upon  the  structure  of  the  liver  and  the  kid- 
neys, and  never  allude  once  to  the  brain;  when  the  fact  is, 
alcohol's  principal  effect  is  upon  this  organ,  and  the  functions 
of  this  organ  so  far  transcend  the  functions  of  all  the  others, 
that,  I  might  say,  there  is  no  comparison." 

Some  authors  hold  that  the  alterations  in  the  tissues  by 
alcoholic  drinks  result  from  the  injury  to  the  nerve  centers 
that  preside  over  these  tissues  ;  for  their  nutrition  depends 
not  merely  on  the  direct  effect  of  the  blood  and  lymph  supply, 
but  also  upon  the  direct  influences  of  the  nerve  centers ;  they 
even  go  so  far  as  to  maintain  that  there  is  a  special  set 
of  nerve  fibers  devoted  to  the  control  of  the  nutrition  of  the 
cells,  and  these  nerve  fibers  they  call  "  trophic  nerves  "  or 
"trophic  fibers." 

"  It  is  clear  that  the  nervous  centers,  independently  of  the 
ill  effects  on  their  nutrition  by  the  blood  changes,  have  a  cer- 
tain chemical  attraction  for  alcohol,  which  accordingly  is 
found  in  their  tissue."  - —  GROT  HERS. 

Dr.  Crothers,  in  common  with  many  plrysicians,  regards 
inebriety  as  a  disease. 

Dr.  Clum,  in  his  work  entitled  Inebriety,  its  Causes,  its 
Results,  its  Remedy,  says,  "  The  most  important  part  of  man 


276  EFFECTS   OF  ALCOHOL. 

is  his  nervous  system;  the  cerebrospinal,  sympathetic,  and 
vasomotor  being  intimately  interwoven  and  connected,  com- 
posing the  whole.  The  great  nervous  center,  the  brain,  with 
its  hemispheres,  its  gray  and  white  matter,  is  the  most  com- 
plex of  all  complexities.  The  nerve  fibers  not  only  connect 
every  cell  with  every  other  cell,  but  unite  all  nervous  struc- 
tures into  one,  making  the  entire  body  a  complete  whole,  and 
forming  close  and  direct  sympathy  between  the  intellect  and 
the  physical  organization. 

"  The  mind  and  body  are  so  intimately  connected  that  ex- 
hausting excess  of  either  acts  and  reacts  on  the  other.  Exces- 
sive work,  either  intellectual  or  physical,  the  sudden  loss  of 
property,  intense  disappointment,  great  trouble,  unrequited 
affections,  etc.,  may  impart  a  shock  to  the  senses  through  the 
mind,  which,  extending  to  the  molecules  of  the  brain,  disturbs 
their  normal  action  ;  and  a  sufferer  thus  worn  and  debilitated 
with  the  cares  of  life,  with  an  enfeebled  will-power,  the  result 
of  nervous  exhaustion,  experiences  a  craving  for  some  form 
of  stimulant  to  '  brace  him  up.'  He  is  on  the  verge  of  ine- 
briety, or  of  insanity,  or  both ;  and  if  he  indulges  in  alcoholic 
beverages  he  becomes  an  inebriate.  Any  disease  inherited  or 
acquired,  acting  either  directly  or  indirectly  upon  the  nervous 
system,  may  act  as  the  predisposing,  exciting,  or  complicating 
and  protracting  cause  of  alcoholic  inebriety. 

"  Inebriety  is  often,  too  often,  observed  to  flourish  in  the 
richest  and  most  promising  soil.  The  clergyman,  the  lawyer, 
the  editor,  the  student,  and  all  others  who  use  their  intellec- 
tual faculties  to  excess,  as  well  as  the  mechanic,  the  laborer, 
and  those  who  excessively  exert  their  physical  system,  have 
unnatural  longings  for  something  to  restore  the  exhausted 
energies  of  mind  and  body. 

"  The  excessive  worry  of  one  man,  the  exhausting  excesses 
of  another,  and  the  overwork  of  others,  lead  to  organic  lesions 


EFFECTS   OF  ALCOHOL.  277 

and  nervous  defects,  and  the  disease  inebriety,  an  ungovern- 
able craving  for  alcoholic  drinks,  is  the  result. 

"  When  a  man  drinks  to  excess,  even  though  forced  to  do 
so  by  a  diseased  nervous  system,  Christian  communities  usually 
brand  him  as  a  criminal,  as  an  outcast,  and  say,  '  We  have 
no  sympathy  for  you ;  stop  drinking  and  be  a  man/  when 
in  reality  the  man  should  be  cared  for,  and  treated  as  other 
diseased  human  beings.  The  fact  that  the  desire  for  alcoholic 
drinks  is  often  a  disease  which  may  be  either  inherited  or 
acquired  is  overlooked  by  those  who  condemn  the  drunkard. 
Our  ancestors  have  for  ages  been  addicted  to  habits  of  intox- 
ication ;  and  we,  their  descendants,  are  tainted  with  the  disease 
inebriety." 

MORAL  DETERIORATION  PRODUCED  BY  ALCOHOL. 

[FROM  MARTIN'S  The  Human  Body  and  the  Effects  of  Narcotics.} 

"  One  result  of  a  single  dose  of  alcohol  is  that  the  control 
of  the  will  over  the  actions  and  emotions  is  temporarily  en- 
feebled ;  the  slightly  tipsy  man  laughs  and  talks  loudly,  says 
and  does  rash  things,  is  enraged  or  delighted  without  due 
cause.  If  the  amount  of  alcohol  be  increased,  further  diminu- 
tion of  will-power  is  indicated  by  loss  of  control  over  the 
muscles.  Excessive  habitual  use  of  alcohol  results  in  perma- 
nent over-excitement  of  the  emotional  nature,  and  enfeeblement 
of  the  will ;  the  man's  highly  emotional  state  exposes  him  to 
special  temptations,  to  excesses  of  all  kinds,  and  his  weakened 
will  decreases  the  power  of  resistance  ;  the  final  outcome  is 
a  degraded  moral  condition.  He  who  was  prompt  in  the  per- 
formance of  duty  begins  to  shirk  that  which  is  irksome,  energy 
gives  place  to  indifference,  truthfulness  to  lying,  integrity  to 
dishonesty;  for  even  with  the  best  intentions  in  making 
promises  or  pledges  there  is  no  strength  of  will  to  keep  them. 


278  NARCOTICS. 

In  forfeiting  the  respect  of  others,  respect  for  self  is  lost  and 
character  is  overthrown.  Meanwhile  the  passion  for  drink 
grows  absorbing;  no  sacrifice  is  too  costly  which  secures  it. 
Swift  and  swifter  is  now  the  downward  progress.  A  mere 
sot,  the  man  becomes  regardless  of  every  duty,  and  even  inca- 
pacitated for  any  which  momentary  shame  may  make  him 
desire  to  perform. 

"  For  such  a  one  there  is  but  one  hope,  —  confinement  in  an 
asylum,  where,  if  not  too  late,  the  diseased  craving  for  drink 
may  be  gradually  overcome,  the  prostrated  will  regain  its 
ascendency,  and  the  man  at  last  gain  the  victory  over  the 
brute." 

NARCOTICS. 

Gould's  Dictionary  of  Medicine,  one  of  the  very  best 
authorities,  thus  defines  narcotic  :  "  a  drug  that  produces  nar- 
cosis" and  narcosis,  as  "  the  deadening  of  pain,  or  the  pro- 
duction of  incomplete  or  complete  anesthesia  by  the  use  of 
narcotic  agents,  such  as  the  use  of  anesthetics,  opium,  and 
other  drugs."  It  is  common,  however,  to  treat  of  chloroform, 
ether,  chloral  hydrate,  etc.,  in  a  group  by  themselves  under 
the  designation  Anesthetics. 

The  Century  Dictionary  thus  defines  narcotic :  "  a  sub- 
stance which  directly  induces  sleep,  allaying  sensibility  and 
blunting  the  senses,  and  which,  in  large  quantities,  produces 
narcotism  or  complete  insensibility.  Opium,  Cannabis  Indica, 
hyoscyamus,  stramonium,  and  belladonna  are  the  chief  nar- 
cotics, of  which  opium  is  the  most  typical.  Direct  narcotics 
.  .  .  either  produce  some  specific  effect  upon  the  cerebral  gray 
matter,  or  have  a  very  decided  action  on  the  blood-supply 
of  the  brain." 

Some  authorities  class  alcohol  with  the  narcotics. 


OPIUM.  279 


OPIUM. 

Opium  is  the  dried  and  thickened  juice  of  the  head,  or 
capsule,  of  a  species  of  poppy.  Incisions  are  made  in  the  par- 
tially ripened  heads ;  the  milky  juice  exudes  ;  after  about 
twenty-four  hours  the  partially  dried  and  thickened  material 
is  scraped  off  with  a  dull  knife.  Most  of  the  opium  comes 
to  this  country  from  Smyrna,  with  a  smaller  quantity  from 
Constantinople.  As  gathered  it  is  *a  reddish-brown,  sticky 
substance  of  peculiar  odor.  It  is  soluble  in  water,  alcohol,  and 
dilute  acids,  to  all  of  which  it  gives  a  deep  brown  color.  It 
is  a  very  complex  substance ;  but  the  chief  constituent  is  mor- 
phia, or  morphine,  to  which  the  properties  of  opium  are  due. 
One-fourth  of  a  grain  of  morphine  is  equal  to  a  grain  of  opium 
of  the  average  strength.  "  Opium  was  known  to  the  Greeks,  but 
was  not  much  used  before  the  seventeenth  century ;  at  present 
it  is  the  most  important  of  all  medicines,  and  its  applications 
the  most  multifarious,  the  chief  of  them  being  for  the  relief 
of  pain  and  the  production  of  sleep.  Its  habitual  use  is  dis- 
astrous and  difficult  to  break  up.  It  is  classed  as  a  stimulant 
narcotic,  acting  almost  exclusively  on  the  central  nervous  sys- 
tem when  taken  internally  ;  in  large  quantities  it  is  a  power- 
ful narcotic  poison,  resulting  in  a  coma  characterized  by  great 
contraction  of  the  pupils,  insensibility,  and  death."  —  Century 
Dictionary. 

The  United  States  Dispensatory  makes  the  following  state- 
ments as  to  its  medical  properties  and  uses :  "  Opium  is  a 
stimulant  narcotic.  Taken  by  a  healthy  person  in  a  moderate 
dose,  it  increases  the  force,  fullness,  and  frequency  of  the 
pulse,  augments  the  temperature  of  the  skin,  invigorates  the 
muscular  system,  quickens  the  senses,  animates  the  spirits, 
and  gives  new  energy  to  the  intellectual  faculties.  Its  opera- 
tion, while  thus  extending  to  all  parts  of  the  system,  is 


280  HASHISH. 

directed  with  peculiar  force  to  the  brain,  the  functions  of 
which  it  excites  sometimes  even  to  intoxication  or  delirium. 
In  a  short  time  this  excitation  subsides;  a  calmness  of  the 
corporeal  actions,  and  a  delightful  placidity  of  mind  succeed  ; 
and  the  individual,  insensible  to  painful  impressions,  forget- 
ting all  sources  of  care  and  anxiety,  submits  himself  to  a  cur- 
rent of  undefined  and  unconnected  but  pleasing  fancies,  and 
is  conscious  of  no  other  feeling  than  that  of  a  quiet  and  vague 
enjoyment.  At  the  end  of  half  an  hour  or  an  hour  from  the 
administration  of  the  narcotic,  all  consciousness  is  lost  in 
sleep.  The  soporific  effect,  after  having  continued  for  eight 
or  ten  hours,  goes  off,  and  is  often  succeeded  by  more  or  less 
nausea,  headache,  tremors,  and  other  symptoms  of  diminished 
or  irregular  nervous  action,  which  soon  yield  to  the  recupera- 
tive energies  of  the  system ;  and,  unless  the  dose  is  frequently 
repeated,  and  the  powers  of  nature  worn  out  by  over-excite- 
ment, no  injurious  consequences  ultimately  result.  Such  is 
the  obvious  operation  of  opium  when  moderately  taken  ;  but 
other  effects,  very  important  in  a  remedial  point  of  view,  are 
also  experienced.  All  the  secretions,  with  the  exception  of 
that  from  the  skin,  are  in  general  either  suspended  or  dimin- 
ished ;  the  peristaltic  motion  of  the  bowels  is  lessened ;  pain 
and  inordinate  muscular  contraction,  if  present,  are  allayed ; 
and  general  nervous  irritation  is  composed,  if  not  entirely 
relieved." 

HASHISH. 

The  following  quotation  from  Bayard  Taylor  is  given  to 
show  the  great  influence  of  a  narcotic  on  the  nervous  system. 
For  a  detailed  account  of  the  effects  of  this  drug  read  the 
chapter  entitled  "  The  Visions  of  Hasheesh "  in  The  Lands 
of  the  Saracen.  "  The  use  of  Hasheesh  —  which  is  a  prepa- 
ration of  the  dried  leaves  of  the  Cannabis  indica  —  has  been 


HABITS.  281 

familiar  to  the  East  for  many  centuries.  During  the  Crusades 
it  was  frequently  used  by  the  Saracen  warriors  to  stimulate 
them  to  the  work  of  slaughter ;  and  from  the  Arabic  term  of 
{  hashasheen/  or  eaters  of  Hasheesh,  as  applied  to  them,  the 
word  '  assassin  '  has  been  naturally  derived." 

It  is  said  that  burglars,  train-robbers,  etc.,  often  drink  be- 
fore their  work  to  "  nerve "  them  for  it,  being  careful,  how- 
ever, not  to  drink  too  much. 

Habits.  —  It  is  well  to  here  emphasize  that  Habits  are 
Acquired  Reflex  Actions. 

The  work  of  the  spinal  cord  is  that  of  a  subordinate  officer, 
whose  duty  is  to  relieve  his  superior,  the  brain,  of  many 
small  tasks,  and  to  afford  him  relief  from  having  all  the 
details  constantly  on  his  mind.  If  we  learn  to  do  many 
things  mechanically,  we  save  the  effort  of  doing  them  by  con- 
scious effort  and  act  of  will.  Whatever  we  do  for  the  first 
time  requires  careful  attention.  To  learn  any  new  muscular 
action,  such  as  a  new  step  in  marching,  fingering  a  musical 
instrument,  or  typewriting,  requires  effort ;  they  produce 
more  or  less  fatigue.  Subsequent  effort  in  doing  the  same 
thing  is  very  much  less,  showing  that,  in  many  cases,  fatigue 
is  mental  rather  than  muscular.  What  we  do  from  habit,  and 
cheerfully,  is  easily  done.  Hence  the  desirability  of  forming 
good  habits,  that  we  may,  without  unnecessary  effort,  that 
is,  without  loss  of  energy,  do  what  is  needed  for  our  well- 
being.  The  habit  of  Resting,  early  formed,  is  of  incalculable 
value  to  any  person,  especially  to  the  student. 

The  student  will  do  well  to  read  such  books  as  Call's 
Power  Through  Repose,  and  Brackett's  Technique  of  Rest. 
They  are  very  suggestive  of  ways  of  economizing  energy. 

We  are  not  conscious  of  expending  energy  in  standing, 
until  we  begin  to  be  weary ;  but  the  fact  that  a  blow  on  the 
head  causes  one  to  fall,  reveals  the  fact  that  the  brain  is 


282  AFFERENT  AND  EFFERENT  IMPULSES. 

constantly  sending  messages  to  the  muscles  to  make  them  act. 
The  shock  of  the  blow  has  stopped  the  sending  forth  of  these 
messages,  and  so  the  body  is  no  longer  supported.  None  of 
the  muscles  that  support  the  body  have  been  injured  or  even 
touched. 

In  studying  the  muscles,  the  fact  was  noted  that  the 
muscles  are  always  slightly  "on  the  stretch."  This  means 
that  nerve  impulses  are  continually  passing  from  the  central 
nervous  system  which  tend  to  keep  the  muscles  in  a  state 
of  slight  contraction. 

We  have,  in  youth,  such  a  boundless  store  of  energy  that 
we  do  not  sufficiently  consider  these  matters.  But  if  one 
wishes  to  follow  the  intellectual  life  long  and  successfully, 
he  must  learn  to  economize  energy,  and  to  direct  his  forces 
into  useful  channels.  And  one  important  part  of  this  knowl- 
edge is  learning  how  to  rest.  It  is  an  art  that  very  few  have 
well  learned. 

The  brain  is  like  a  telegraph  office  in  both  receiving  and 
sending  out  messages.  Unlike  the  telegraph  office,  it  has 
one  set  of  fibers  to  bring  currents  in  (afferent),  and  another 
to  carry  currents  outward  (efferent). 

We  have  concerned  ourselves  thus  far  chiefly  with  efferent 
nerve  fibers  and  efferent  currents.  By  way  of  review  it  may 
be  stated  that  these  efferent  currents  are  sent  mainly  to 
muscles,  to  make  them  shorten  or  to  relax,  or  to  gland-cells 
to  control  their  activity.  The  only  other  efferent  currents,  so 
far  as  known,  are  those  which  possibly  go  to  the  cells  of  the 
tissues  to  regulate  their  nutrition  or  their  heat  production. 

Having  given  so  much  attention  to  the  outgo  of  nerve 
impulses,  let  us  ask  the  question,  "  What  about  the  incoming 
nerve  currents  ?  " 

"  All  life  long  the  never-ceasing  changes  of  the  external 
world  continually  break  as  waves  on  the  peripheral  endings 


AFFERENT  IMPULSES — SENSATIONS.  283 

of  the  afferent  nerves ;  all  life  long  nervous  impulses,  now 
more,  now  fewer,  are  continually  sweeping  inward  toward  the 
center ;  and  the  nervous  metabolism,  which  is  the  basis  of 
nervous  action,  must  be  at  least  as  largely  dependent  on  these 
influences  from  without  as  on  the  mere  chemical  supply  fur- 
nished by  the  blood.  We  must  regard  the  supereminent 
activity  of  the  cortex,  and  the  characters  of  the  processes 
taking  place  in  it,  as  due  not  so  much  to  the  intrinsic  chemical 
nature  of  the  nervous  substance  which  is  built  up  into  the 
cortical  gray  matter,  as  to  the  fact  that  impulses  are  continu- 
ally streaming  into  it  from  all  parts  of  the  body ;  that  almost 
all  influences  brought  to  bear  on  the  body  make  themselves 
felt  by  it.  To  put  the  matter  in  a  bald  way,  we  may  ask  the 
question,  what  would  happen  in  the  cortex  if,  its  ordinary 
nutritive  supply  remaining  as  before,  it  were  cut  adrift  from 
afferent  impulses  of  all  kinds  ?  We  can  hardly  doubt  but 
that  volitional  and  other  psychical  processes  would  soon  come 
to  a  standstill,  and  consciousness  vanish.  This  is,  indeed, 
roughly  indicated  by  the  remarkable  case  of  a  patient  whose 
almost  only  communication  with  the  external  world  was  by 
means  of  one  eye,  he  being  blind  in  the  other  eye,  deaf  of 
both  ears,  and  suffering  from  general  anaesthesia.  Whenever 
the  sound  eye  was  closed  he  went  to  sleep."  —  Text  Book  of 
Physiology,  FOSTER. 

Let  us  turn  from  the  consideration  of  outgoing,  or  efferent, 
nerve  impulses  and  their  resulting  action,  to  the  incoming,  or 
afferent,  nerve  impulses  and  the  activity  which  they  rouse  in 
the  gray  matter  of  the  cerebrum  —  Sensation. 

READIN^J.  —  Wear  and  Tear,  Mitchell. 


CHAPTER   IX. 

THE   SPECIAL   SENSES. 

WE  have  been  considering  the  body  as  a  collection  of 
organs  working  together  to  serve  the  brain,  the  mechanism 
through  which  the  mind  operates. 

We  have  especially  studied  the  muscles  as  the  only  means 
by  which  the  mind  manifests  itself  to  the  outer  world. 

But  how  much  mind  would  we  have  if  we  did  not  receive 
something  from  the  outer  world  ?  Read  the  story  of  Kaspar 
Hauser.  We  are  continually  getting  knowledge  of  the  outer 
world  and  of  the  condition  of  our  own  bodies  through  the 
afferent  nerves.  We  may  never  know  fully  what  conscious- 
ness and  thought  are,  but  we  can  understand  that  to  the 
brain  are  continually  streaming  nerve  impulses  that  convey 
messages  which  the  brain  more  or  less  completely  interprets.  * 

These  incoming  currents  pass  along  myriads  of  nerve 
fibers.  But  the  nerve  fibers  are  all  essentially  alike.  And 
the  kinds  of  sensations  that  these  currents  arouse  in  the 
brain  are  but  few.  It  is  difficult  to  classify  the  senses, 
but  it  will  serve  our  convenience  to  divide  them  into  two 
groups. 

General  Sensations  and  Special  Senses.  —  In  distinc- 
tion from  the  special  senses,  sight,  hearing,  etc.,  are  the 
general  sensations  already  referred  to,  such  as  hunger,  thirst, 
fatigue,  nausea,  satiety, -faintness,  etc.  They  are  often  called 
"  common  sensations  ; "  and  Martin  designates  them  as  "  sen- 
sations which  we  do  not  mentally  attribute  to  the  properties 
of  external  objects,  but  to  the  conditions  of  our  own  bodies." 

284 


CUTANEOUS   SENSATIONS.  285 

What  We  learn  by  touching  Objects.  —  Let  one  person 
rest  the  hand  flat  on  the  table,  palm  upward,  and  close  the 
eyes.  An  object  placed  on  the  palm  may  give  rise  to  various 
sensations,  so  that  it  may  be  described  as  rough  or  smooth, 
light  or  heavy,  hot  or  cold,  wet  or  dry,  etc.  If  the  object  is 
very  heavy  or  very  hot,  it  may  cause  pain.  If  now  the  thumb 
and  fingers  are  raised  and  applied  to  the  object,  more  definite 
information  will  be  gained  as  to  its  shape,  size,  surface,  etc. 
Now  raise  the  object  in  the  hand,  and  further  appreciation 
will  be  gained  as  to  its  weight. 

These  experiments  show  that  several  sensations  are  in- 
volved in  the  handling  of  objects,  and  that  the  knowledge  so 
gained  is  complex. 

The  sensations  from  the  objects  resting  on  the  skin  of  the 
passive  hand  may,  probably,  all  be  referred  to  impressions 
made  on  nerve  endings  in  the  skin,  and  are  called  Cutaneous 
Sensations.  They  include  :  (1)  the  Pressure  Sense,  or  Touch 
proper,  (2)  the  Temperature  Sense,  and  (3)  Pain. 

In  lifting  the  object  muscles  are  employed,  and  the  sensa- 
tion thus  obtained  is  called  the  Muscular  Sense. 

Before  taking  up  these  sensations  singly,  let  us  review  a 
few  features  of  the  nervous  mechanism  concerned. 

Nerve  Endings  in  the  Skin.  —  We  have  learned  that 
the  skin  consists  of  two  layers,  the  epidermis  and  the  dermis. 
We  need  now  to  recall  those  conical  elevations  of  the  dermis 
that  we  call  papillae.  In  these  papillae  are  certain  important 
nerve  endings.  Since  the  sensory  nerve  impulses  pass  from 
without  inward,  it  would  be  more  appropriate  to  speak  of 
the  outer  extremities  of  these  nerves  as  their  beginnings,  or 
origins,  rather  than  as  "  endings."  Still,  as  they  are  peculiar, 
and  are  commonly  termed  endings,  we  may  follow  the  ordinary 
usage. 

There  are  several  kinds  of  nerve  endings  in  the  skin  and 


286 


SENSE   OF  TOUCH. 


underneath,  it  that  receive  the  impressions  which,  carried  to 
the  brain,  gi?e  us  sensations  of  touch  (and  allied  sensations 
to  be  considered  soon). 

It  would  be  out  of  place  to  try  to  go  into  this  matter  fully 
here.  Some  branching  nerves  end  in  the  epidermis.  In  some 
of  the  papillae  are  oval  bodies  in  which  nerve  fibers  end. 
Underneath  the  skin  some  nerve  fibers  end  in  little  bodies 
shaped  like  a  grain  of  wheat.  Pressure  on  the  skin  affects 
these  nerve  endings,  and  starts  impulses  that  pass  along  the 
sensor  fibers  to  some  nerve  center, 
probably  in  the  spinal  cord,  spinal 
bulb,  or  brain. 

These    "Touch    corpuscles"    are 
not  regarded  as  essential  for  pro- 
ducing the  sensation  of  touch,  but 
some  nerve  endings  in  the    skin   do 
seem  necessary ;  for  if  a  nerve  fiber 
be  touched,  not  at  the  end,  but  some- 
where along  its  course,  we  get,  not  a 
sensation  of  touch,  but  a  sensation  of 
pain.     Except  in  the  mouth  and  nose, 
we  get  little,  if  any,  sense  of  touch 
from  any  organ  but  the  skin.     The  lin- 
ing of  the  digestive  tube  and  the  internal  organs  generally  are 
devoid  of  this  sense.     Compare  Fig.  86  with  Figs.  50  and  51. 
The  Sense  of  Touch.  —  Of  the  special  senses  the  most 
general   is  that  of  Touch,       Seeing  and  hearing,   taste  and 
smell,  belong  to  very  limited  parts  of  the  outside  of  the  body, 
but  we  have  the  power  of  feeling  all  over  the  surface  of  the 
body.    ' 

Not  only  is  the  sense  of  touch  the  most  general  in  being 
distributed  over  the  whole  of  the  body,  but  it  is  the  most 
widely  distributed  sense  throughout  the  animal  kingdom.  As 


Fig.  86.     Papilla  of  Shin  with 
Touch  Corpuscle. 


PRESSURE  SENSE.  287 

we  descend  the  animal  scale  we  find  many  of  the  lower 
animals  lacking  some  of  the  senses  that  we  possess.  But 
here  we  must  be  careful  in  our  statements.  Because  an 
earthworm,  for  instance,  lacks  eyes,  we  may  not  say  that  it 
lacks  sight.  That  is,  while  there  is  pretty  good  evidence  that 
it  cannot  see  objects  distinctly  as  we  can,  it  is  not  therefore 
necessarily  unable  to  distinguish  between  light  arid  darkness. 
Many  of  the  lower  animals  lacking  eyes  show  that  they 
discern  light.  In  many  of  the  simpler  forms  of  animal  life 
there  is  110  evidence  of  a  sense  of  hearing;  and  it  is  extremely 
likely  that  if  they  have  taste  and  smell,  these  senses  are  in 
a  very  rudimentary  state  of  development.  But  in  all  these 
forms  it  is  believed  that  " feeling"  exists.  Contact  of  their 
exterior  with  foreign  objects  is  so  often  immediately  followed 
by  action  that  little  doubt  remains  about  their  having  the 
sense  of  touch.  Even  ameba  may  have,  in  a  rudimentary 
state,  the  power  to  distinguish  light,  to  taste,  to  hear.  Still 
we  have  little  or  no  evidence  on  these  points,  while  we  are 
pretty  sure  that  it  feels. 

Further,  the  organs  of  special  sense,  and  the  nervous  sys- 
tem generally,  may  be  said  to  originate  in  the  skin,  and  to  be 
modifications  of  the  sense  of  touch.  It  has  long  been  known 
that  the  brain  and  spinal  cord  originate  as  an  infolding  of 
the  skin,  which  afterward  becomes  completely  shut  off  from 
the  outer  surface.  "  In  general,  it  may  be  said  that  a  study 
of  the  facts  of  development  shows  us  that  nerve-cells  appear 
at  first  upon  the  surface  of  the  body,  but  that  during  the 
growth  of  the  organism  the  cells  become  shut  off  from  the 
surface;  and  in  order  to  maintain  their  connection  with 
the  periphery,  long  processes  called  nerves  pass  from  the 
cells  thus  deeply  imbedded  to  the  surface." 

The  Pressure  Sense.  —  The  sense  of  touch,  proper,  is 
strictly  a  Pressure  Sense.  If  we  test  the  skin  to  find  what 


288  LOCALIZATION  OF  TOUCH. 

regions  are  able  to  detect  the  least  pressure,  it  is  found  that 
the  forehead  is  most  sensitive,  and  nearly  equally  so  are  the 
temples,  back  of  the  hand,  and  forearm. 

The  ability  to  detect  differences  of  pressure  is  tested  by 
finding  what  is  the  least  addition  to  a  weight  required  to 
make  it  seem  heavier.  For  instance,  if  a  weight  of  11  grains 
is  just  perceptibly  heavier  than  one  of  10  grains,  it  does  not 
follow  that  1  grain  added  to  a  weight  of  100  grains  will 
give  any  palpable  increase.  To  100  grains  must  be  added  10 
grains  before  additional  pressure  is  felt ;  that  is,  whatever  the 
weight,  there  must  be  the  same  ratio  of  increase  to  increase 
the  sensation.  This  is  part  of  the  law,  already  stated,  of  the 
relation  of  stimulus  and  sensation.  The  law  is  true  only  in 
a  general  way,  and  will  not  apply  in  extreme  cases.  It  is 
stated  that  the  forehead,  the  lips,  and  temples  appreciate  an 
increase  of  one-fortieth  to  one-thirtieth  of  the  weight  esti- 
mated, while  the  skin  of  the  hand,  the  fingers,  and  the  forearm 
require  an  increase  of  one-twentieth  to  one-tenth  for  its  per- 
ception. 

Discrimination  of  difference  of  pressure  is  more  keen  if 
weights  are  applied  in  rapid  succession  on  the  same  spot  than 
when  applied  at  different  places  or  after  an  interval  of  time. 
The  weights  used  in  these  tests  should  press  on  equal  areas  of 
the  skin. 

The  lingering  effect  of  pressure,  or  After-Pressure,  may  be 
noticed  after  taking  off  a  tight  hat,  skate-strap,  shoe,  or  glove. 

The  Localization  of  Touch-Sensations.  —  We  can  usu- 
ally locate  very  accurately  any  skin  sensation.  "  If  a  point  of 
the  skin  is  touched,  certain  tactile  corpuscles  are  irritated ; 
these,  in  turn,  set  up  impulses  in  sensory  nerve  fibers,  and 
these  impulses  are  carried  by  the  fibers,  first  to  the  spinal 
cord,  and  then  to  the  brain,  where  the  fibers  end  in  ganglionic 
masses  in  the  gray  matter  of  the  cerebral  cortex.  There  are 


LOCAL   SIGN.  289 

thus  projected,  as  it  were,  on  the  cortex  of  the  brain,  tactile 
centers  for  the  hind  leg,  fore  leg,  neck,  eye,  ear,  trunk,  etc. ; 
and  it  follows  that  each  point  of  the  skin  has  a  corresponding 
point  in  the  cerebral  cortex.  Thus  for  each  stimulation  of  a 
point  of  the  cerebral  cortex  there  is  a  Local  Sign,  and  thus  we 
localize  tactile  impressions."  The  accuracy  varies,  and  is 
ordinarily  keenest  where  the  nerves  are  most  numerous. 
Where  the  sense  of  locality  seems  to  be  improved  by  cultiva- 
tion, this  appears  to  be  due  to  keener  discrimination  in  the 
brain-cells,  and  not  to  changes  in  the  nerves  or  nerve  endings. 
This  is  indicated  in  the  fact  that  if  the  fingers  of  one  hand 
become  more  discriminating  by  practice,  it  will  be  found  that 
the  fingers  of  the  other  hand,  without  special  training,  are  also 
improved. 

The  delicacy  of  localizing  touch  is  usually  tested  in  this 
way.  The  blunted  points  of  a  light  pair  of  compasses  are 
allowed  to  rest  gently  on  the  skin  of  various  parts  of  the 
body.  If  the  two  points  are  very  close  together  they  will  be 
felt  as  one  pressure.  That  part  which  can  best  distinguish,  as 
two  points  of  touch,  these  blunt  points,  is  considered  the 
most  sensitive.  By  this  test  the  tip  of  the  tongue  is  the 
most  sensitive,  being  able  to  distinguish,  as  two  separate 
points  of  contact,  the  tips  of  the  compasses  when  only  one 
twenty-fifth  part  of  an  inch  apart.  Following  is  the  order  of 
degrees  of  sensitiveness  :  tip  of  tongue,  tips  of  fingers,  lip,  tip 
of  nose,  eyelid,  cheek,  forehead,  knee,  neck ;  while  the  middle 
of  the  back  seems  least  sensitive,  the  two  points  not  produ- 
cing two  distinct  sensations  until  they  are  more  than  two  and 
a  half  inches  apart.  In  general  those  parts  which  are  most 
used,  and  those  parts  which  are  more  freely  movable,  are  most 
sensitive ;  for  instance,  the  knee  is  much  more  sensitive  than 
the  middle  of  the  thigh  or  the  middle  of  the  leg,  and  the 
elbow  than  the  middle  of  the  arm  or  forearm.  If  the  compass 


290  ILLUSIONS   OF  TOUCH. 

points,  about  half  an  inch  apart,  be  passed  from  the  palm  to 
the  tips  of  the  fingers,  it  will  at  first  seem  one  line  gradually 
separating  into  two  diverging  ones,  owing  to  the  keener  local- 
izing power  as  the  finger-tips  are  approached. 

"  The  reference  of  the  sensations  aroused  by  the  excite- 
ment of  definite  nerve-cells  to  definite  parts  of  the  periphery  is 
a  power  acquired  through  the  physiological  experiences  of  the 
earliest  months  of  life.  Through  the  sense  of  sight  the  seat 
of  irritation  is  recognized,  and  through  muscular  sensation  its 
relation  to  surrounding  parts  is  experimentally  explored,  so 
that  cumulative  harmonious  experiences  of  tactile,  visual, 
and  muscular  sensations  finally  bring  into  correspondence  the 
various  areas  with  definite  varieties  of  touch  sensation."  • 
SEWALL. 

The- skin  is  more  sensitive  when  moist;  the  barber  there- 
fore moistens  the  ball  of  his  thumb  before  feeling  the  edge  of 
the  razor  to  see  if  it  is  sharp  enough. 

Illusions  of  Touch.  —  Aristotle's  experiment  has  already 
been  mentioned.  If  the  "  funny  bone,"  or  "  crazy  bone,"  be 
hit,  i.e.,  if  the  ulnar  nerve  be  bruised  against  the  bone,  sharp 
pain  may  be  felt  in  the  wrist  and  hand,  and  soreness  of  these 
parts  may  be  felt  for  days,  though  they  are  not  in  the  least 
injured,  but  only  the  nerve  at  the  elbow.  The  currents  along 
this  nerve  rouse  sensation  that  we  have  learned  to  localize  at 
the  endings  of  the  nerve  fibers.  So,  too,  after  amputation  of 
a  hand  or  foot,  there  may  for  years  be  sensations  referred  to 
the  missing  member,  probably  due  to  irritation  of  the  nerves 
of  the  stump.  There  is,  then,  no  certainty  of  getting  rid  of  a 
corn  by  amputating  a  toe. 

The  Temperature  Sense.  —  Many  cases  are  on  record  in 
which,  from  accident  or  disease,  the  pressure  sense  was  lost 
and  the  temperature  sense  retained,  or  vice  versa.  Such  facts 
have  led  to  the  belief  that  the  temperature  sense  is  distinct 


TEMPERATURE  SENSE.  291 

from  that  of  touch,  and  has  its  own  nerve  fibers  and  nerve 
endings. 

Since  heat  and  cold  are  only  differences  in  the  degree  of 
heat,  we  would  expect  both  of  these  kinds  of  impressions  to 
be  received  through  one  set  of  nerves.  There  seems,  how- 
ever, to  be  good  evidence  of  two  sets  of  nerve  fibers,  one  for 
heat  and  the  other  for  cold.  In  the  common  experience  of 
the  foot  "  going  to  sleep  "  by  pressure  on  the  sciatic  nerve,  or 
the  arm  from  compression  of  the  brachial  nerve,  the  skin  may 
be  found,  at  a  certain  stage,  to  be  only  slightly  sensitive  to 
warmth,  while  distinctly  sensitive  to  cold.  In  some  diseases 
of  the  spinal  cord  the  skin  may  be  affected  by  warmth  but 
not  by  cold.  The  sensations  of  cold  and  pressure  seem  to  be 
usually  lost  or  retained  together,  while  those  of  warmth  and 
pain  have  a  similar  connection.  But  more  accurate  results 
are  obtained  by  touching  the  skin  with  a  blunt  metal  pencil, 
warmed  or  cooled.  If  this  be  applied  at  regular  close  inter- 
vals it  is  found  that  some  places  feel  the  warm  point,  while 
others  feel  the  cold.  In  this  way  the  skin  may  be  mapped 
out  into  "  warm  spots  "  (warmth-perceiving  spots),  and  "  cold 
spots  "  (cold-perceiving  spots),  and  still  other  areas  seem  not 
sensitive  to  temperature.  Heat  or  cold,  if  applied  directly  to 
a  nerve  trunk,  does  not  rouse  sensations  of  temperature,  but, 
if  strong  enough,  produces  pain.  If  the  elbow  be  dipped  into 
water  at  the  freezing-point,  a  sensation  not  of  cold  but  of  pain 
is  caused,  and  is  felt  in  the  hand.  Heat  and  cold  are  not  felt 
in  the  digestive  tube  except  at  or  near  the  openings.  If  very 
hot  liquid  be  swallowed,  it  may  cause  pain  in  the  gullet  and 
stomach.  If  a  considerable  quantity  of  warm  liquid  be  taken, 
it  may  give  a  feeling  of  warmth  from  its  effect  on  the  skin  of 
the  abdomen,  by  conduction  of  heat  outward.  As  with  other 
senses,  a  sudden  change  in  the  degree  of  the  stimulus  is  more 
certain  to  rouse  sensation  than  a  gradual  change. 


292  MUSCULAR   SENSE. 

The  Muscular  Sense.  —  As  an  example,  we  will  take  the 
case  of  estimating  the  weight  of  an  object  by  holding  it  in  the 
hand.  Our  estimate  is  thought  by  some  to  be  the  result  of 
(1)  direct  consciousness  of  the  degree  of  effort  put  forth; 
but  probably  it  is  (2)  a  sensation,  or  complex  of  sensations, 
aroused  by  nerve  impulses  from  the  organs  used.  There  are 
afferent  nerve  fibers  with  endings  in  (1)  the  skin,  (2)  the 
muscles  and  tendons,  (3)  the  joints.  In  extending  the  arm 
and  moving  it  up  and  down,  all  three  of  these  sets  of  nerve 
endings  are  probably  stimulated,  and  impulses  thence  con- 
veyed to  the  brain. 

It  is  matter  of  doubt  whether  or  not  the  impulses  from  the 
muscles  are  predominant,  and  consequently,  whether  the  term 
"  muscular  sense "  is  the  most  appropriate.  Peciiliar  nerve 
endings  have  been  found  in  the  tendons,  and  the  joints  are 
believed  to  have  an  especially  rich  nerve  supply.  It  is  not 
necessary  that  we  actively  use  the  muscles  to  have  sensations 
of  this  kind.  In  passive  moments,  as  the  raising  of  the  arm 
by  another  person,  we  have  a  "  sense  of  position  "  of  the 
parts,  a  considerable  share  of  which  is  probably  due  to  the 
tension  of  the  skin  and  changes  in  the  joints.  There  is,  of 
course,  some  tension  of  the  muscle,  even  in  this  passive  move- 
ment, that  might  affect  nerve  endings  in  it.  The  muscular 
sense  is  closely  related  to  the  general  sensibility  already  men- 
tioned, if  not  a  modified  form  of  it. 

It  is  difficult  to  realize  the  importance  of  this  sense  in  our 
daily  experience.  We  probably  underestimate  it,  and  attrib- 
ute to  sight  too  much  of  our  knowledge  of  the  external  world. 
The  fundamental  facts  concerning  the  objects  about  us  are 
not  obtained  through  sight  alone.  Such  knowledge  is  based 
on  complex  judgments  concerning  the  meaning  of  auditory 
and  visual  phenomena,  according  as  they  have,  in  past  expe- 
rience, been  interpreted  by  tactile  and  muscular  perceptions. 


MUSCULAR   SENSE.  293 

That  is,  when  reduced  to  its  simplest  terms,  our  most  practi- 
cal and  important  knowledge  of  the  world  is  the  outgrowth  of 
tactile  and  muscular  perceptions  ;  by  and  with  them  all  other 
sense-perceptions  have  been  corrected  and  compared. 

"  The  fundamental  education  concerning  the  outer  world, 
which  engages  the  earliest  years  of  every  child,  consists  in 
accumulating  and  systematizing  with  other  sense-perceptions 
tactile  and  muscular  impressions  of  objects.  A  sensation  is 
no  sooner  felt  than  some  muscular  movement,  involving  a 
definite  muscular  feeling,  is  made  by  which  the  character  of 
the  sensation  is  changed  and  experimentally  tested  under 
different  conditions.  The  physiological  process  involved  in 
building  up  sense-knowledge,  therefore,  embraces  in  alterna- 
tion sensation  excited  by  external  objects,  motion  accompanied 
by  muscular  sensation,  and  change  in  original  sensation.  In 
other  words,  the  motor  and  sensory  impulses  form  a  sort  of 
balance,  and  both  are  necessary. 

"  When  we  consider  that  it  is  through  muscular  sensation 
that  we  derive  our  most  accurate  conceptions  of  the  form, 
weight,  and  position  of  objects,  and  through  which  we  explore 
our  own  body  surface,  and  distinguish  its  areas  of  localiza- 
tion ;  that  this  is  the  fundamental  sense  by  which  the  sensa- 
tions arising  in  most  other  organs  are  tested  and  verified,  and 
that  it  is  from  the  sense  of  muscular  movement  that  we  can 
form  ideas  of  time  and  space,  it  may  well  be  regarded  as  the 
mother  of  all  sense-perceptions.  Normal  muscles,  even  when 
functionally  inactive,  are  still  in  a  state  of  tonic  contraction ; 
it  is  not  improbable  that  this  tone  is  a  reflex  action  whose 
sensory  element  is  formed  by  the  impulses  traveling  along 
nerves  of  muscular  sensation.  Such  impulses  are  probably 
indispensable  to  the  preservation  of  the  equilibrium  of  the 
body."  —  SEWALL. 

An  illustration  of  the  assistance  which  touch  and  the  mus- 


294  PAIN. 

cular  sense  give  to  the  sense  of  sight  is  furnished  in  the  case 
of  a  boy  who  had  been  blind  from  birth,  and  received  sight  at 
the  age  of  twelve  years  by  means  of  a  surgical  operation. 
At  first  he  could  not  distinguish  a  globe  from  a  circular  card 
of  the  same  color  until  he  had  touched  them.  He  knew  the 
peculiar  features  of  the  dog  and  the  cat  by  feeling,  but  not  by 
sight.  Happening  one  day  to  pick  up  the  cat,  he  recognized 
for  the  first  time  the  connection  between  the  new  sense  of 
sight  and  the  old  familiar  ones  of  touch  and  the  muscular 
sense.  On  putting  the  cat  down  he  said,  "  So,  puss,  I  shall 
know  you  next  time." 

Pain.  —  When  a  heavy  weight  is  laid  on  the  hand  it  may 
cause  pain.  It  would  at  first  seem  that  the  ordinary  pressure 
sense,  when  unduly  exaggerated,  becomes  pain.  But  there 
seem  good  reasons  for  considering  pain  as  a  distinct  sense 
from  that  of  touch  intensified.  It  is  thought  that  there  are, 
throughout  all  parts  of  the  body,  nerves  of  "common  sensi- 
bility" or  "general  sensibility,"  which  keep  the  nerve  centers 
informed  as  to  the  condition  of  all  the  various  tissues,  and  that 
ordinarily  we  have  no  sensation  resulting  from  the  impulses ; 
to  use  the  language  of  the  psychologist,  "they  do  not  rise 
above  the  threshold  of  consciousness."  They  may  have 
some  influence  in  adjusting  the  action  of  the  different  parts. 
We  have  seen  how  the  blood  flow  to  any  part  is  continually 
adjusted  without  our  knowing  anything  about  it.  But  we 
are"  usually  more,  or  less  conscious  of  the  general  condition  of 
the  body.  We  call  by  the  name  of  "common  sensations" 
such  feelings  as  hunger,  thirst,  nausea,  fatigue,  depression, 
melancholy,  restlessness,  such  as  many  experience  preceding 
a  thunderstorm,  the  feeling  of  general  discomfort  known  as 
malaise,  and  its  opposite,  the  feeling  of  general  well-being. 
The  body  seems  to  have  a  set  of  nerves  to  give  information  as 
to  the  state  of  nutrition  of  the  body,  and  as  to  its  condition 


PAIN.  .  295 

generally.  These  nerves,  when  the  system  is  disordered  in 
any  part,  may  bring  messages  that  cause  intense  pain.  Of 
course,  they  are  warnings  (they  are  more  than  mere  warnings ; 
probably  if  the  earlier  indications  of  simple  discomfort  had 
been  heeded,  the  later  more  emphatic  messages  of  pain  would 
not  have  been  necessary).  These  messages  of  pain  demand 
attention. 

In  reference  to  pain  in  the  skin,  it  is  held  that  the  skin, 
too,  has  its  nerves  of  general  sensibility,  and  that  these  are 
distinct  from  those  of  touch  and  temperature  sense.  That 
when  they  are  unduly  stimulated  they  give  rise  to  painful 
sensations.  It  is  to  be  noted  that  the  internal  organs  are 
ordinarily  devoid  of  feeling,  and  that  the  skin  is  especially 
sensitive.  The  skin  senses  stand  guard  at  the  outposts,  so  to 
speak,  of  the  body's  camp,  and  give  warning  of  approaching 
danger.  No  enemy  may  enter  without  being  discovered  by 
these  keen  sentinels,  and  the  alarm  is  given.  If  it  is  not 
heeded,  great  harm  may  follow.  And  it  is  a  comfort  to  know 
that  the  more  severe  wounds  do  not  cause  pain  in  proportion 
to  their  extent.  When  a  person  says  his  "  lungs  are  sore " 
the  pain  is  usually  in  the  muscles  of  fche  chest  from  coughing. 
While  there  may  be  acute  pain  from  the  lungs,  as  in  pleurisy, 
there  is  often  deep-seated  lung  disease  without  pain  from  the 
lungs  themselves.  The  muscles  of  the  chest  and  back  may  be 
strained  by  lifting,  and  the  soreness  is  erroneously  attributed 
to  the  lungs  or  kidneys.  Hence  there  is  frequently  a  wholly 
needless  apprehension  of  deep-seated  disorder,  whereas  in 
reality  there  is  merely  a  strain  of  superficial  muscles.  In 
amputating  a  limb  the  chief  pain  is  in  cutting  through  the 
skin.  Some  excellent  authorities  still  hold  the  view  that  pain 
is  merely  the  result  of  intensifying  any  of  the  simple  sen- 
sations ;  but  it  is  generally  held  that  it  results  from  the 
excessive  stimulation  of  the  nerves  of  general  sensibility ;  as 


296  UUNGER  AND   THIRST. 

Foster  puts  it,  "The  constantly  smoldering  embers  of  com- 
mon sensibility  may  be  at  any  moment  fanned  into  the  flame 
of  pain." 

In  the  real  "special  senses,"-— sight,  hearing,  smell,  taste, 
touch,  and  temperature  sense,  —  we  refer  the  sensation  to  some 
external'  object,  whereas  general  sensations  are  subjective, 
referred  to  our  bodies.  Ordinarily  we  do  not  localize  the 
common  sensations,  and  a  farther  indication  of  the  relation- 
ship of  pain  and  general  sensation  is  in  the  lack  of  complete 
localization  of  pain.  Slight  pain,  especially  in  the  skin,  may 
be  closely  located,  but  severe  pain  tends  to  become  indefinite 
and  diffuse.  So  we  may  class  both  the  muscular  sense  and  pain 
with  the  "  general  "  rather  than  with  the  "  special  "  senses. 

Hunger  and  Thirst.  —  The  cause  of  these  sensations  in  a 
healthy  body  is  plainly  the  need  of  food  and  water  throughout 
the  system  generally.  The  sensation  of  thirst  manifests  itself 
in  the  throat,  and  the  longing  may  be  temporarily  relieved  by 
merely  moistening  the  throat.  So  hunger  may,  for  the  time, 
be  appeased  by  filling  the  stomach  with  indigestible  material. 
But  the  sensation  soon  returns.  The  system  has  a  crying 
need,  and  it  is  not  to  be  put  off  by  any  such  frauds.  That 
these  sensations  are  really  demands  made  by  the  body  as  a 
whole  may  be  shown  by  the  fact  that  they  are  permanently 
relieved  by  introducing  food  and  water  into  the  body  (by  the 
rectum,  for  instance),  in  which  case  the  throat  and  stomach 
have  nothing  given  them  directly.  Since,  however,  food  and 
drink  naturally  enter  by  the  throat  and  stomach,  the  mucous 
membrane  of  these  organs  has  become  spokesman  of  the  body 
for  its  demands. 

The  Sense  of  Taste.  —  We  have  seen  that  the  tongue  is 
a  very  muscular  organ,  and  that  when  we  are  eating  it  helps 
to  keep  the  food  between  the  teeth,  and  that  it  does  the  chief 
part  of  the  work  in  beginning  the  process  of  swallowing. 


SENSE  OF  TASTE.  297 

We  have  also  seen  that  the  tip  of  the  tongue  has  a  very 
keen  sense  of  touch.  By  means  of  its  mobility  and  sensitive- 
ness the  tongue  hot  only  aids  in  mastication,  but  also  cleanses 
the  teeth  afterward  by  detecting  and  removing  small  particles 
of  food  from  the  teeth. 

The  sense  of  taste  helps  us  in  judging  of  the  fitness  of 
anything  that  presents  itself  as  a  candidate  for  election  as 
food.  By  reflex  action  the  taste  of  agreeable  substances  aids 
in  digestion  by  stimulating  the  glands,  especially  the  salivary 
glands. 

The  surface  of  the  tongue  is  covered  with  Papillae  These 
are  of  three  kinds.  Most  numerous  are  the  Filiform  papillae, 

Papillae 


Glosso-pharyn- 
geal  Nerve (9th) 


Gustatory  Branch  of 
Fifth  Nerve 

Fig,  87.     Diagram  of  Tongue,  showing  Nerves  and  Papillae. 

slender,  cylindrical  projections.  Like  the  papillae  of  the  skin, 
they  seem  to  be  organs  of  touch.  Scattered  among  the  fili- 
form papillae  are  small,  bright  red  spots,  which  on  examina- 
tion are  found  to  be  shaped  somewhat  like  a  mushroom,  the 
Fungiform  papilla?.  Near  the  base  of  the  tongue  are  about  a 
dozen  larger  papillse,  arranged  like  a  letter  V  with  its  apex 
toward  the  base  of  the  tongue.  These  are  the  Circumvallate 
papillae,  each  having  around  it  a  deep  circular  furrow. 

On  the  sides  of  this  furrow  are  small  oval  bodies  called 


298  SENSE  OF  SMELL. 

"  taste  buds,"  connected  with  the  ends  of  the  nerves  of  taste. 
The  nerves  of  taste  are  the  Glosso-pharyngeal  or  ninth  cranial 
nerves,  distributed  to  the  back  part  of  the  tongue,  and  a  branch 
of  the  fifth  pair  of  nerves,  the  Gustatory,  to  the  front  part. 

Although  we  ordinarily  speak  of  an  article  of  food  as  "  pal- 
atable," or  "  unpalatable,"  the  sense  of  taste  in  the  palate  is 
only  feebly  developed. 

Substances  must  be  dissolved  before  they  can  be  tasted. 
If  the  tongue  be  wiped  dry  and  a  few  grains  of  salt  or  sugar 
be  placed  on  it,  the  taste  will  not  be  perceived  for  a  little  time. 
Insoluble  substances  give  no  taste. 

What  we  call  Flavors  affect  us  more  through  the  sense  of 
smell  than  through  taste.  If  the  nose  be  held  shut,  and  we 
are  careful  about  breathing,  a  piece  of  onion  placed  on  the 
tongue  does  not  produce  what  we  usually  call  the  taste  of 
the  onion.  We  may  thus  get  rid  of  the  disagreeable  part  of 
taking  certain  medicines.  Let  the  student  experiment  with 
various  substances  as  above  indicated. 

It  is  said  that  the  temperature  of  about  40  degrees  F.  is 
most  favorable  for  tasting ;  and  after  rinsing  the  mouth  with 
very  hot  or  very  cold  water,  such  bitter  substances  as  quinine 
will  have  only  a  trace  of  their  usual  taste. 

The  tip  of  the  tongue  seems  to  be  most  sensitive  to  sweets 
and  salines,  the  back  part  to  bitters,  and  the  sides  to  acids. 

The  Sense  of  Smell.  —  "  The  sense  of  odor  gives  us  in- 
formation as  to  the  quality  of  food  and  drink,  and  more  espe- 
cially as  to  the  quality  of  the  air  we  breathe.  Hence  we  find 
the  organ  placed  at  the  opening  of  the  respiratory  passages 
and  in  close  proximity  to  the  organs  devoted  to  taste.  Taste 
is  at  the  gateway  of  the  alimentary  canal,  just  as  smell  is  the 
sentinel  of  the  respiratory  tract ;  and  just  as  taste,  when  com- 
bined with  smell  to  give  the  sensation  we  call  flavor,  influences 
the  digestive  process,  and  is  influenced  by  it,  so  smell  influ- 


SENSE  OF  SMELL. 


299 


Olfactory  Bulb 


Olfactory  Nerves. 

Branches  of 
Fifth  Nerve 

Turbinated  Bones  : 


ences  the  respiratory  process.  The  presence  of  odors  influ- 
ences both  the  amplitude  and  the  number  of  the  respiratory 
movements.  Thus  the  smell  of  wintergreen  notably  increases 
the  respiratory  work,  next  comes  ylang-ylang,  and  last  rose- 
mary. The  breathing  of  a  fine  odor  is  therefore  not  only  a 
pleasure,  but  it  increases  the  amplitude  of  the  respiratory 
movements.  Just  as  taste  and  flavor  influence  nutrition  by 
affecting  the  digestive  process,  and  as  the  sight  of  agreeable 
or  beautiful 
objects  and 
the  hearing 
of  melodious 
and  harmo- 
nious sounds 
react  on  the 
body  an  d 
help  physio- 
logical well-being,  so  the 
odors  of  the  country,  or 
even  those  of  the  per- 
fumer, play  a  beneficent 
role  in  the  economy  of 
life."—  JVFKENDRICK 
and  SNODGRASS. 

In  quiet  breathing  the  air  passes  along  the  lower  air  pas- 
sages just  above  the  hard  palate.  The  true  olfactory  passages 
are  higher,  but  still  in  communication  with  this  lower  pas- 
sage. When  we  wish  to  test  the  quality  of  the  air,  we  sniff, 
that  is,  make  a  sudden  inspiration  by  jerking  the  diaphragm 
down,  and  air  from  the  outside  then  rushes  into  these  upper 
nasal  passages,  over  the  walls  of  which  the  nerves  of  smell, 
the  Olfactory  Nerves,  are  spread  in  the  mucous  membrane. 
The  sudden  rush  of  air  against  this  membrane  seems  to  aid 


Fig.  88.    Nerves  of  the  Outer  Wall  of  the 
Nasal  Cavity. 


300  SENSE  OF  SIGHT. 

greatly  in  getting  the  odor.  The  nerves  have  peculiar  end- 
ings, and  it  is  not  known  just  how  the  substances  produce 
their  effect.  The  substances  must  be  in  a  very  finely  divided 
state,  probably  gaseous.  The  mucous  membrane  is  supplied 
with  mucus,  and  the  odorous  substance,  probably,  is  first  dis- 
solved in  the  mucus.  The  lower,  or  respiratory,  passages 
have  a  more  abundant  blood  supply,  and  are  redder  than  the 
upper.  In  inflammation,  owing  to  their  narrowness,  the  pas- 
sages, especially  the  upper,  are  often  closed  by  contact  of  the 
opposite  sides.  Substances  like  ammonia  have  no  odor,  but 
excite  the  tactile  nerves.  They  are  often  spoken  of  as  hav- 
ing a  "pungent"  odor,  but  are  simply  irritants. 

The  Sense  of  Sight.  —  In  the  fable  of  the  blind  man 
carrying  the  lame  man.  whose  eyes  were  good,  we  have  an 
illustration  of  the  dependence  of  the  various  organs  on  each 
other.  AVe  have  considered  how  all  our  knowledge,  both  of 
the  condition  of  our  bodies  and  of  the  external  world,  comes 
through  the  nervous  system.  Now,  so  far  as  the  senses  we 
have  studied  are  concerned,  we  learn  almost  nothing  of  the 
external  world  except  from  actual  contact.  But  sight  reveals 
objects  at  a  distance.  Without  the  eye  the  body  is  compara- 
tively helpless.  The  lame  man  that  the  body  carries  is  a 
slight  burden  in  comparison  with  the  assistance  which  he  ren- 
ders. We  can1  well  afford  to  carry  with  us  all  the  time  two  of 
these  lame  men  to  keep  posted  as  to  the  objects  beyond  our 
reach.  Of  course  touch  is  a  great  aid  to  our  interpretations 
of  what  we  see.  But  sight  is  evidently  the  main  avenue  of 
knowledge,  the  royal  road  along  which  come  the  messages 
which  bring  us  the  most  news,  which  give  us  the  keenest 
delight,  which  make  us  aware  of  most  that  we  know  of  this 
world,  and  the  only  means  of  knowing  that  there  are  other 
worlds  than  the  one  we  inhabit. 

In  order  to  understand,  in  any  clearness,  the  action  of  the 
eye,  we  ueect  to  examine  into  its  structure. 


MUSCLES   OF  EYEBALL.  301 

A  model  of  the  eye  should  also  be  used  in  connection  with 
the  dissection,  but  it  alone  will  not  make  the  structure  clear. 

The  Muscles  of  the  Eyeball.  —  With  bone-forceps  or  a 
strong  knife  cut  away  the  bone  at  the  outer  angle  of  the  eye- 
socket  of  the  rabbit  (almost  any  mammal  will  serve  for  this, 
though  the  bone  is  so  thick  in  the  calf  or  sheep  that  it  will  be 
difficult  work  without  the  aid  of  a  good  pair  of  bone-forceps). 

1.  With  scissors  trim  away  the  white  membrane  around 
the  front  of  the  white  of  the  eye  ;  this  was  continuous  with  the 
lining  of  the  eyelid,  and  is  the  Conjunctiva. 

2.  Find  a  muscle  running  along  the  roof  of  the  eye-socket, 
which  passes  through  a  loop  of  tendon,  near  the  edge  of  the 
orbit,  and  turns  backward  and  outward  to  its  attachment  to 
the  top  of  the  eyeball.     This  is  the  Superior  Oblique  Muscle. 

3.  Beneath  the  eye  find  a  muscle  having  its  origin  in  the 
inner  front  part  of   the  socket,  and  passing  outward,  to  be 
inserted  in  the  lower  surface  of  the  eyeball.     This  is  the  Infe- 
rior Oblique  Muscle. 

4.  Four  straight  muscles,  the  Superior,  Inferior,  Internal, 
and  External  Recti,  are  attached  to  the  top,  bottom,  and  sides 
of  the  eyeball ;  find  the  origin  of  these,  with  that  of  the  supe- 
rior oblique,  at  the  posterior  extremity  of  the  eye-socket. 

5.  Dissect  away  these  muscles  with  any  fat  or  other  tissue, 
and  find,  extending  from  the  back  of  the  eye,  the  cylindrical 
Optic  Nerve. 

External  Parts  of  the  Eye.  —  The  eye  of  the  rabbit  may 
be  used,  but  that  of  the  ox  is  better. 

1.  Observe  the  clear  front  part  of  the  eye,  the  Cornea. 
Note  its  shape.     Its  wider  end  was  at  the  inner  angle  of  the 
eyelids. 

2.  Around  the  cornea  find  a  whitish  membrane,  the  Con- 
junctiva, which,  a  short  distance  back  from  the  cornea,  sepa- 
rates from  the  eyeball  to  turn  forward  and  line  the  eyelid. 


302 


STRUCTURE   OF  EYE. 


3.  The    severed    muscles  of   the    eyeball,   a  mass  of   fat 
which  forms  a  cushion  for  the  eye,  and  other  tissue,  should 
be  trimmed  away,  leaving  the  Optic  Nerve. 

4.  Place  the  eye  in  its  natural  position,  and  make  draw- 
ings of  it,  as  seen  from  the  front  and  from  one  side,  naming 
the  parts. 

Ciliary  Muscle 


Optic  Nerve  Choroid 

Fig.  89.     Horizontal  Section  of  Right  Eye. 

Dissection  of  the  Eye.  —  Each  member  of  the  class 
should  have  an  eye  to  dissect.  To  supply  a  large  class  it  is 
best  to  send  to  a  slaughtering-house  in  the  nearest  large  city. 
If  the  eye  muscles  and  other  external  parts  have  already 
been  studied,  it  will  not  be  necessary  to  remove  the  muscles 
and  fat  around  the  eye  ;  in  fact,  they  may  well  be  left  un- 
touched, as  they  serve  as  a  cushion  to  support  the  eye  during 
dissection.  The  eye  may  conveniently  be  dissected  on  a 


DISSECTION   OF  EYE.  303 

small  piece  of  board  or  shingle  ;  and  if  it  is  desirable  to  turn 
the  eye,  it  is  better  to  do  so  by  turning  the  support,  as  the 
eye  usually  sticks  to  the  support,  and  the  dissection  may  be 
injured  by  trying  to  move  it. 

CAUTION.  —  After  the  eye  is  opened  be  careful  not  to  com- 
press it.  If  the  eye  be  held  in  the  hand  while  trying  to  cut 
its  tough  outer  coat,  the  jelly-like  contents  are  easily  squeezed 
out,  ruining  the  dissection.  Let  the  eye  rest  on  the  board  all 
the  time,  and  after  first  cutting  through  the  cornea  it  is  not 
necessary  nor  advisable  to  touch  it  with  the  fingers. 

1.  Lay  the  eye  on  the  board,  with  the  cornea  uppermost. 
Hold  the  eye  firmly  with  the  thumb  and  fingers  of  one  hand  ; 
with  the  thumb  and   forefinger  of  the  other  hand   hold  the 
blade  of  the  scalpel  half  an  inch  from  its  tip  ;  with  a  steady 
motion  push  the  blade  horizontally  through  the  cornea,  near 
its  edge. 

2.  The  liquid  in  the  cavity   back  of  the  cornea  is  the 
Aqueous  Humor. 

3.  Slightly  enlarge  the   cut  horizontally  ;  then  with  the 
forceps  take  hold  of  the  upper  edge  of  the  cut,  and  with  the 
scissors  cut  around  the  margin  of  the  cornea  and  remove  it. 

4.  The  dark  membrane  now  exposed  is  the  Iris.     Pinch  the 
eye  slightly  at  the  sides  to  make  the  iris  show  more  distinctly. 
The  hole  in  its  center  is  the  Pupil.     With  the  forceps  raise  the 
edge  of  the  iris  around  the  margin  of  the  pupil  to  see  that  it 
is  here  unattached  to  the  structures  underneath.    Observe  the 
color  and  markings  of  the  iris. 

5.  From  one  end  of  the  pupil  cut  outward  to  the  outer 
margin  of  the  iris  ;  then  cut  around  its  outer  margin  and  re- 
move it.     Observe  the  color  and  markings  of  the  posterior 
surface. 

6.  The  body  now  laid  bare  is  the  Crystalline  Lens.    Touch  it. 

7.  Lay  a  piece  of  newspaper  close  to  the  eye,  on  which  to 


304:  DISSECTION  OF  EYE. 

receive  the  lens,  which  sometimes  pops  out  suddenly.  AVitli 
a  sharp  knife  make  a  quick,  light  gash  across  the  surface  of 
the  lens  to  cut  through  the  thin  coat  which  envelops  it,  the 
Lens  Capsule.  Usually  the  lens  may  be  made  to  come  out 
by  applying  gentle  pressure  to  the  sides  of  the  eye  with  the 
thumb  and  finger.  If  not,  enlarge  the  opening  thus  made, 
and  carefully  pry  out  the  lens  with  the  handle  of  the  forceps, 
noting  closely,  in  so  doing,  the  difference  between  the  front 
and  back  surfaces.  Lay  the  lens  on  the  piece  of  newspaper, 
and  look  through  it  at  the  letters.  Make  a  drawing  of  the 
lens  as  seen  from  the  front,  and  as  seen  from  one  side,  naming 
the  front  and  back  surfaces. 

8.  In  removing  the  strip  of  eye-coating,  as  directed  below, 
be  extremely  careful  not  to  drag  the  clear  jelly-like  vitreous 
humor.     The  parts  must  be  lifted  gently  by  the  forceps,  and 
if  the  clear  jelly-like  mass  adheres,  it  must  be  cut  through, 
horizontally,  with  the  scissors.     With  the  scissors  now  cut 
outward  about  one-half  of  an  inch  from  the  edge  of  the  hole 
made  in  the  front  of  the  eye  ;  then  cut  clear  around  the  eye 
and  remove  a  strip  of  this  width,  thus  enlarging  the  opening 
before  made.     On  the  inside  of  the  strip  removed  there  may 
be  found  radiating  black  ridges,  the  Ciliary  Processes. 

9.  Carefully  pick  away  with  the  forceps,  and  snip  away 
with  the  scissors,  everything  on  the  surface  of  the  clear  mass 
beneath. 

10.  The  substance  filling  the  remainder  of  the  eye-cavity  is 
the  Vitreous  Humor. 

11.  Through  the  vitreous  humor  the  entrance  of  the  optic 
nerve  may  be  seen  with  the  blood  tubes  radiating  from  it.     If 
necessary,  carry  the  dissecting  board  to  a  window  to  let  the 
light  enter  from  above. 

12.  The  tough  outer  coat  of  the  eye  is  the  Sclerotic  Coat. 

13.  Inside  the  sclerotic  is  the  dark  Choroid  Coat. 


THE  RETINA.  305 

14.  The  inner,  nearly  transparent,  pinkish  or  whitish  coat 
is  the  Retina.  At  this  stage  of  the  dissection  it  has  probably 
become  slightly  wrinkled,  and  the  white  ridges  may  be  seen 
radiating  from  the  entrance  of  the  optic  nerve. 

Drag  out  the  vitreous  humor,  and  note  the  soft,  whitish  or 
pinkish  retina ;  observe  that  it  is  a  continuation  of  the  optic 
nerve.  Tear  away  the  retina,  noting  its  consistency.  Note 
the  color  and  luster  of  the  inner  surface  of  the  choroid  coat. 
The  dark  layer  on  the  inside  of  the  choroid  coat  is  the  pig- 
ment-la}7er  (outer  part)  of  the  retina,  which  adheres  to  the 
choroid,  and  is  torn  loose  from  the  rest  of  the  retina. 

The  reflection  of  light  from  this  surface  of  the  choroid  coat 
causes  the  color  seen  in  the  eyes  of  some  animals.  Turn  the 
remaining  coats  inside  out,  and  tear  the  choroid  coat  from 
the  sclerotic.  Observe  the  blood  tubes  passing  from  one  to 
the  other. 

The  Retina.  —  The  chief  thing  in  the  eye  is  the  retina. 
Without  this  all  else  is  useless.  If  light  of  sufficient  strength 
falls  on  the  retina.it  stimulates  elements  in  the  outer  layer 
(rods  and  cones),  and  the  nerve  impulses,  thus  started,  pass 
along  the  fibers  of  the  optic  nerve  to  the  brain,  and  we  have 
the  sensation  of  light.  But  in  order  to  see  anything  distinctly, 
the  light  must  fall  on  the  retina  in  such  a  way  as  to  form 
a  distinct  image  of  that  object.  If  the  lens  be  removed,  or 
becomes  opaque,  as  in  "cataract/'  we  fail  to  see  distinctly, 
though  we  may  discern  light  from  darkness.  The  other  parts 
of  the  eye  exist  to  form  images  on  the  retina.  The  cornea, 
lens,  and  the  aqueous  and  vitreous  humors  are  the  parts 
directly  concerned  in  forming  the  images.  Light  from  an 
object  passes  through  the  cornea,  aqueous  humor,  lens,  and 
vitreous  humor,  and  the  rays  are  so  refracted  as  to  form  an 
inverted  image.  If  this  image  falls  on  a  good  retina  we  see 
well.  If  these  parts  do  not  all  work  well  we  see  poorly. 


306 


THE  RETINA. 


The  retina  is  very  complicated  in  its  structure.  No  less 
than  eight  layers  have  been  distinguished,  as  shown  in  Fig. 
90.  Of  these  layers  the  outermost,  the  layer  of  the  rods 
and  cones,  is  the  one  directly  concerned  in  appreciating  the 
differences  in  the  vibrations  of  the  light. 

The  rays  of  light  pass  through  the  retina,  and  produce 
their  effect  on  the  rods  and  cones  which  constitute  the  outer 


Inner  or  Vitreous  Surface 


I 

Internal  Limiting  Layer 

Layer  of  Nerve  Fibers 
Layer  of  Nerve  Cells 


Inner  Molecular  Layer 

Inner  Nuclear  Layer 

Outer  Molecular  Layer 

Outer  Nuclear  Layer 
External  Limiting  Layer 
Layer  of  Rods  and  Cones 

Layer  of  Pigment  Cells 

Outer  or  Choroid  Surface 

Fig.  90.     Diagrammatic  Section  of  the  Human  Retina. 

(back)  layer ;  and  the  nerve  impulses  aroused  by  the  light 
must  return  through  the  thickness  of  the  retina  to  be  conveyed 
along  the  nerve  fibers  of  the  innermost  layer  of  the  retina  to 
the  optic  nerve. 

The  Center  of  Distinct  Vision.  —  Near  the  middle  of 
the  back  part  of  the  retina  is  the  Yellow  Spot  (macula  lutea)t 


PROTECTION   OF  EYE.  307 

and  in  the  center  of  this  a  slight  hollow.     In  this  region  vision 
is  most  distinct,  especially  for  color. 

Protection  of  the  Eye.  —  The  outer  coat  holds  all  in 
place,  and  gives  strength  for  attachment  of  the  muscles  that 
give  motion  to  the  eyeball.  The  Lacrymal  Gland,  or  tear 
gland,  is  just  above  the  outer  angle  of  the  eye,  and  pours  its 
secretion  over  the  eyeball  in  weeping,  or  when  there  is  need 
of  an  unusual  supply  of  tears.  The  lids  serve  as  curtains  to 
admit  or  shut  out  light,  and,  by  winking,  with  their  own  secre- 
tion, a  fluid  mixture  of  salt  water  and  mucus,  to  wash  the  eye. 
It  is  as  though  a  man  were  kept  all  the  time  in  front  of  a 
plate-glass  window,  with  water  and  rubber  scraper,  to  keep 
it  clean  and  bright.  The  lacrymal  secretion  is,  ordinarily, 
carried  off  as  fast  as  it  is  made,  by  two  ducts  beginning  at  the 
inner  angle  of  the  eye,  one  on  each  lid ;  these  two  ducts  soon 
unite,  and  empty  by  one  outlet  into  the  nasal  cavity.  If  these 
ducts  are  stopped,  or  if  the  secretion  be  formed  very  rapidly, 
the  liquid  overflows  on  the  face  as  tears.  Then,  too,  the  eye- 
ball is  set  well  in  its  bony  socket  to  shield  it  from  harm.  The 
cornea,  or  window,  is  a  continuation  of  the  sclerotic  coat. 

The  choroid  coat  is  richly  supplied  with  blood  tubes  and 
dark  pigment  to  absorb  light  so  it  may  not  be  reflected  about 
in  the  eye.  The  choroid  coat,  continued  forward,  becomes  the 
iris,  but  is  incomplete,  leaving  the  circular  hole  in  this  dark 
curtain.  The  pupil  looks  dark  because  we  are  looking  into  a 
dark  room.  A  thin  membrane,  called  the  hyaloid  membrane, 
lines  the  inner  surface  of  the  retina.  Arising  from  the  scle- 
rotic coat  at  the  outer  border  of  the  iris  is  a  muscle,  the  ciliary 
muscle ;  it  is  inserted  at  the  margin  of  the  lens  by  means  of 
fibrous  strands  that  form  an  intimate  part  of  the  capsule 
inclosing  it. 

Take  a  single  lens  that  is  convex  on  both  sides,  such  as  in  - 
the  common  tripod  lens,  or  any  hand  magnifier.    Hold  this  up 


308 


FOR    DISTANCE. 


Fig.  91.     The  Formation  of  an  Image  on  the  Retina. 


in  front  of  a  window,  and  catch  the  inverted  image  of  the 
window  on  a  piece  of  paper  held  back  of  the  lens.  This  illus- 
trates how  the  image  of  an  external  object  is  formed  by  the 

crystalline  lens  upon 
the  retina  of  the  eye. 
If  two  lenses  of  dif- 
ferent thickness  can 
be  obtained,  it  will  be 

86611   that    the    thicker 

lens  (if  both  have  the 

same  diameter)  will  make  an  image  closer  to  the  lens  than 
the  thinner  one. 

Adjustment  of  the  Lens  for  Seeing  at  Different  Dis- 
tances. —  If  we  look  up  from  a  book  we  are  reading,  we  do 
not  realize  that  any  change  is  necessary  in  the  eye  for  us  to 
see  a  distant  object.  But  it  is  easy  to  prove  that  we  cannot, 
at  the  same  time,  see  distinctly  a  near  and  a  distant  object. 

Stick  a  pin  at  each  end  of  a  book  cover.  Hold  the  book  at 
about  the  usual  distance  for  reading,  so  that  the  two  pins  are 
in  a  line  with  the  eye.  Look  closely  at  the  nearer  pin,  and 
the  second  pin  will  appear  indistinct.  Now  look  closely  at 
the  head  of  the  farther  pin.  The  nearer  one  may  be  seen,  but 
not  sharply.  Another  way  of  testing  this  :  hold  the  tip  of  a 
pencil  in  a  line  with  any  object,  say  a  picture,  on  a  wall  oppo- 
site. In  looking  at  the  tip  of  the  pencil  the  picture  is  dim. 
Now  look  by  the  pencil  at  the  picture,  and  the  point  of  the 
pencil  will  be  blurred. 

What  changes  does  the  eye  make  to  enable  it  to  see 
clearly,  now  a  near,  now  a  far  object? 

When  the  photographer  places  his  camera,  he  moves  the 
ground-glass  plate  back  and  forth  till  the  image  is  distinctly 
formed  on  the  plate.  We  cannot  move  the  retina  back  and 
forth,  so  we  change  the  shape  of  the  lens.  When  we  look  at 


FAR    AND    NEAR    SIGHT. 


309 


a  near  object  the  lens  becomes  thicker,  and  when  we  look  at  a 
distant  object  the  lens  becomes  less  thick.  In  looking  at  an 
object  that  is  near,  the  ciliary  muscle  pulls  on.  the  hyaloid 
membrane,  and  draws  it  forward  (since  the  muscle  is  fastened 
at  the  point  where  the  iris  joins  the  cornea).  When  the 
hyaloid  membrane  is  pulled  forward,  the  lens  is  released  from 
pressure  that  was  given  it  by  the  lens  capsule.  Now  the  lens 
becomes  thicker  because  it  is  elastic,  and  when  it  is  not  sub- 
ject to  pressure  it  tends  to  become  relatively  thick.  When 
we  look  at  a  distant  object  the  muscle  relaxes,  and  the  cap- 
sule presses  on  the  front  of  the  lens  and  flattens  it,  so  ad- 


CILIARY  MUSCLE 


FAR  NEAR  CILIARY  PROCESS 

Fig.  92.     A  Diagram  to  Illustrate  Accommodation. 


justing  for  far  sight.  It  should  be  noted  that  adjustment 
for  near  sight  is  brought  about  by  muscular  effort,  hence  is 
fatiguing;  whereas  adjustment  for  far  sight  is  accomplished 
mechanically,  without  effort.  In  old  age  the  lens  usually  be- 
comes less  elastic,  and  cannot  adjust  for  near  sight.  Since  it 
is  unable  to  grow  more  convex,  artificial  lenses  (eyeglasses) 
may  be  used  to  enable  one  to  see  near  objects  clearly.  Most 
elderly  people  see  fairly  well  at  a  distance,  but  use  glasses  for 
reading  or  any  close  work. 

In  "  near-sighted  "  eyes,  the  eyeball  is  often  too  long  from 
front  to  back,  so  the  image  is  not  thrown  on  the  retina.  Con- 
cave glasses  remedy  this  defect.  The  eye  may  also  be  too 


310  THE    HLIND    SPOT. 

short,  and  need  special  glasses.  The  refracting  surfaces  (cor- 
nea or  lens)  may  be  unequally  curved,  causing  astigmatism. 
For  most  of  these  defects  the  occulist  will  supply  suitable 
glasses. 

The  Blind  Spot.  —  The  structure  of  the  retina  is  exceed- 
ingly complicated,  much  more  so  than  any  of  the  other  nerve 
endings.  Light  must  fall  on  these  special  structures  to  have 
any  effect.  Falling  on  the  optic  nerve  itself  has  no  effect  in 
giving  a  sensation  of  light.  And  if  the  light  falls  on  the 
spot  where  the  optic  nerve  enters  the  eyeball  we  see  nothing. 
At  the  left  (as  looked  at  by  the  class)  of  a  long  blackboard 
make  a  bright  circular  spot,  three  inches  in  diameter,  with 
white  or  yellow  crayon.  Beginning  at  the  right  of  this,  write 
the  figures  1,  2,  3,  etc.,  along  the  whole  length  of  the  board, 
about  eight  inches  apart.  Let  each  pupil  close  the  right  eye 
and  look  at  the  bright  spot.  Then  let  each  read  the  figures, 
passing  slowly  from  one  to  another  in  order,  at  the  same  time 
noticing  whether  the  bright  spot  can  be  seen.  To  succeed  in 
this  the  eye  must  not  be  allowed  to  waver.  Have  the  pupils 
tell  when  the  bright  spot  disappears,  then  read  on,  and  note 
when  the  spot  reappears. 

In  the  following  experiment  shut  the  right  eye,  and  be 
careful  not  to  let  the  left  eye  waver. 

Read  this  line  slowly.  Can  you  see  the  star  all  the  time  ? 
If  the  star  does  not  disappear  before  reaching  the  end  of  the 
line,  let  the  eye  travel  on  across  the  right-hand  page,  or  hold 
the  book  nearer  the  face.  In  the  human  eye  the  optic  nerve 
enters  the  eye  not  in  the  center,  but  nearer  the  nose,  so  that 
in  turning  the  left  eye  toward  the  right  at  the  proper  angle, 
the  image  of  the  star  falls  upon  the  spot  where  the  optic 
nerve  enters.  As  this  spot  is  insensitive  to  light,  the  star  no 
longer  appears. 

The  optic  nerve,  while  capable  of  carrying  nerve  impulses 


COLOR    VISION.  311 

that  cause  sensations  of  light,  is  not  itself  sensitive  to  light. 
If  the  optic  nerve  be  cut,  it  does  not  give  pain,  but  gives  the 
sensation  of  a  flash  of  light. 

While  most  of  the  fibers  from  each  optic  nerve  cross  to 
the  other  side  of  the  brain,  some  fibers  go  to  the  same  side 
of  the  brain.  We  can  therefore  better  understand  the  close 
sympathy  that  we  know  exists  between  the  two  eyes.  In 
many  of  the  lower  animals,  a  fish,  for  instance,  the  two  optic 
nerves  cross  without  any  intermingling  of  fibers. 

Pain,  felt  in  the  eyes,  comes  from  impulses  conveyed,  not 
by  the  optic  nerve,  but  by  a  branch  of  the  fifth  pair  of  nerves 
(the  nerves  of  sensation  for  most  of  the  face). 

Regulation  of  the  Amount  of  Light  Admitted  into  the 
Eye.  —  Hold  a  hand-glass  between  the  face  and  a  well-lighted 
window.  Note  the  size  of  the  pupils.  Quickly  turn  toward 
the  darkest  part  of  the  room.  We  see,  what  we  have  all 
noticed  in  watching  the  eyes  of  a  cat,  that  when  subject  to  a 
bright  light  the  pupil  is  small,  but  with  less  light  the  pupil  is 
larger.  The  iris  has  circular  muscle  fibers  that  reduce  the 
pupil  when  .there  is  too  much  light  for  the  eye,  and  when 
the  light  is  feeble  the  pupil  opens  wider. 

Color  Sensations.  —  The  difference  in  colors  is  due  to  the 
differences  in  the  rapidity  of  the  vibrations  of  the  waves 
of  light,  as  in  sound  differences  in  the  rapidity  of  the  vibra- 
tions of  the  sound  waves  cause  the  various  degrees  of  pitch. 
Many  interesting  experiments  may  be  made  with  color  sensa- 
tion, most  of  which  are  difficult  of  explanation.  Fasten  a 
bright'  red  wafer  or  seal  on  a  white  card.  Look  intently  at 
the  center  of  the  red  spot  till  the  eye  is  tired.  Then  quickly 
look  at  a  point  in  the  white  surface.  What  color  appears  ? 
This  may  be  repeated  with  other  colors. 

Color  Blindness.  —  It  is  found  that  some  persons  cannot 
distinguish  certain  colors.  Blindness  to  red  and  green  are 


312  STEREOSCOPIC    VISION. 

most  common.  This  is  a  matter  of  importance  among  railroad 
men  and  sailors,  where  it  is  necessary  to  distinguish  red  and 
green  signals. 

Stereoscopic  Vision.  —  In  looking  at  an  object  with  one 
eye  there  is  seen  more  to  the  side  of  that  eye,  while  the  other 
eye  sees  more  of  the  other  side,  considerable  of  the  object 
being  seen  with  both  eyes.  The  effects  produced  on  the  two 
eyes  are  united,  and  so  we  better  see  objects  as  solids.  This 
is  what  is  termed  stereoscopic  or  Binocular  Vision. 

Duration  of  Impressions  of  Light.  —  Most  boys  have 
amused  themselves  around  a  bonfire  by  whirling  a  stick  with 
a  glowing  coal  on  its  end.  The  continuous  circle  of  light  thus 
produced  indicates  that  the  impression  of  light  remains  for  a 
time,  in  this  case  until  the  stick  completes  the  circle,  giving 
a  continuous  line  of  light.  By  Shaking  the  hand  up  and  down 
rapidly  the  same  effect  may  be  produced ;  that  is,  we  see  the 
hand  in  all  positions  at  the  same  time.  Or  when  riding  in  a 
carriage  the  spokes  of  the  wheels  blur  together  because  the 
impression  of  each  lingers  till  another  has  taken  its  place. 
But  if  we  shut  the  eyes  quickly,  we  may  keep  distinct  the 
impression  of  the  last  positions,  and  so  see  them  distinct  from 
each  other.  Better  still,  shut  the  eyes  while  looking  at  the 
wheel,  then  open  and  shut  them  as  quickly  as  possible. 

Again,  if  one  looks  at  a  bright  lamp  and  then  closes  the 
eyes,  there  may  remain  the  same  appearance  as  when  we 
looked  at  the  object  itself.  This  is  called  the  Positive  After- 
image. Or  sometimes,  especially  after  looking  long  at  a 
bright  light,  we  may,  on  closing  the  eyes  or  looking  away, 
see  a  dark  spot  of  the  same  shape  as  the  bright  one  we  looked 
at.  This  is  called  the  Negative  After-image. 

The  Care  of  the  Byes.  —  1.  In  reading  we  wish  light  from 
the  printed  page.  Hence  we  should  avoid  light  entering  the 
eye  from  any  other  source  at  this  time.  While  reading,  then, 


CARE    OF    THE    EYES.  313 

do  not  face  a  window,  another  light,  a  mirror,  or  white  wall, 
if  it  can  be  avoided.  In  a  room,  white  walls  are  likely  to 
injure  the  eyes.  Choose  a  dark  color  for  a  covering  for  a 
reading-table.  Sewing  against  the  background  of  a  white 
apron  has  worked  serious  mischief.  Direct  sunshine  very 
near  the  book  or  table  is  likely  to  do  harm. 

2.  Preferably  have  the  light  from  behind  and  above.     Many 
authors   say   "from  the  left,"   or  "over  the   left   shoulder." 
In  writing  with  the  usual  slant  of  the  letters  this  may  be 
desirable.     But  vertical  writing  is   now  strongly  advocated, 
as  it  enables  one  to  sit  erect,  and  have  the  light  from  above 
and  equally  to  the  two  eyes.     Having  stronger  light  for  one 
eye  than  for  the  other  is   bad.     Sitting  under  and  a  little 
forward  of  a  hanging  lamp  will  thus  give  the  light  equally 
to  the  two  eyes  and  send  no  light  direct  into  the  face.     In 
reading   by  daylight   avoid   cross-lights    so   far   as   possible. 
The  incandescent  electric  light  has   an  advantage  in  being 
readily  lighted,  without  matches,  and  in  giving  out  little  heat, 
thus  making  it  valuable  for  house-lighting ;  but  owing  to  its 
irregular  illumination  (due  to  the  shadow  cast  by  the  wire 
or  filament),  it  is  not  well  suited  for  study  or  other  near  work. 
For  this  purpose  an  Argand  gas  or  kerosene  burner  is  much 
to  be  preferred,  since  it  throws  a  soft,  uniform,  and  agreeable 
light  upon  the  work. 

3.  Reading  out-of-doors  is  likely  to  injure   the  eyes,  es- 
pecially when  lying  down.     To  try  to  .read  while  lying  in  a 
hammock  is  bad  in  many  ways.     Too  much  light  directly  en- 
ters the  eye,  and  often  too  little  falls  upon  the  printed  page. 

4.  Do  not  hold  the  book  or  work  nearer  the  eyes  than  is 
necessary.     So  far  as  possible  avoid  continuous  reading  in  large 
or  heavy  books  by  artificial  light.     Such  books  being  hard 
to  hold,  the  elbows  gradually  settle  down  against  the  sides 
of  the  body,  and  thus,  without  thinking  about  it,  the  book 


314  CARE   OF  THE  EYES. 

is  held  too  close  to  the  eyes,  or  at  a  bad  angle,  or  the  body 
assumes  a  bad  position. 

5.  Frequently  rest  the  eyes  by  looking  up  and  away  from 
the  work,  especially  at  some  distant  object.     One  may  rest 
the  eyes  while  thinking  over  each  page  or  paragraph,  and 
thus  really  gain  time  instead  of  losing  it. 

6.  Have  light  that  is  strong  enough.     Remember  that  the 
law  of  the  intensity  of  light  as  affected  by  distance  is  that  at 
twice  the  distance  from  the  source  of  light  the  light  is  only 
one-fourth  as   strong.     Beading  just  before   sunset  is  risky. 
One  is  often  tempted  to  go  on,  not  noticing  the  gradual  dimi- 
nution of  light. 

7.  Save  the  easiest  reading  for  the  evening.     Newspapers, 
as  a  rule,  have  neither  good  print  nor  good  paper.     If  the 
eyes  have  much  work  to  do,  finish  this  kind  of  reading  by 
daylight  if  possible,  and  by  artificial  light  read  books,  which 
usually  have  better  type  and  better  paper.     In  all  ways  en- 
deavor to  favor  the  eyes  by  doing  the  most  difficult  reading 
by  daylight,  and  saving  the  better  print  and  the  books  that 
are  easier  to  hold   for  work  by  artificial  light.     Writing  is 
usually  much  more  trying   to    the  eyes    than   reading.     By 
carefully  planning  his  work  the  student  may  economize  eye- 
sight, and  it  is  desirable  that  persons  blessed  with  good  eyes 
should  be  careful,  as  well  as  those  who  have  a  natural  weak- 
ness in  the  eyes  ;  for  it  often  results  that  those  inheriting 
weak  organs,  by  taking  proper  care,  may  outlast  and  do  more 
and   better   work   than   those    naturally    stronger,    but   who 
through  carelessness  injure  organs  by  improper  use  or  wrong 
use  (ab-use). 

8.  Reading  before  breakfast  by  artificial  light  is  usually 
bad. 

9.  Many  eyes  are  ruined  during  convalescence.     At  this 
time  the  whole  system  is  often  weak,  including   the   eyes. 


CARE  OF  THE  EYES.  315 

Still,  there  is  a  strong  temptation  to  read,  perhaps  to  while 
away  the  time,  perhaps  to  make  up  for  lost  time  in  school 
work.  This  is  a  time  when  a  friend  may  show  his  friendship 
by  reading  aloud  to  the  convalescent. 

10.  If  one  finds  himself  rubbing  his  eyes,  it  is  a  clear 
sign  that  they  are  irritated.     It  may  be  time  to  stop  reading. 
At  any  rate,  one  should  find  the  cause,  and  not  proceed  with 
the  work  unless  the  irritation  ceases.     If  any  foreign  object 
gets   into  the  eye,  as   a  cinder,  it  is   better  not  to  rub  the 
eye,  but  to  draw  the   lid   away  from  the  eyeball  and  wink 
repeatedly ;    the  increased   flow  of   tears   may   dissolve  and 
wash  the  matter  out.     If  you  must  rub,  rub  the  other  eye. 
If  it  be  a  sharp-cornered  cinder,  rubbing  may  merely  serve 
to  fix  it  more  firmly  in  the  cornea  or  the  mucous  membrane 
of  the  inner  surface  of  the  eyelid.     If  it  does  not  soon  come 
out,  the  lid  may  be  rolled  up  over  a  pencil,  taking  hold  of 
the  lashes  or  the  edge  of  the  lid.     The  point  of  a  blunt  lead 
pencil  is  a  convenient  and  safe  instrument  with  which  to 
remove  the  particle.     Sometimes  being  out  in  the  wind  (espe- 
cially if  unused  to  it),   together  with  bright  sunlight,  may 
irritate  the  eyes.     If  after  such  exposure  one  finds  lamplight 
irritating,  he  will  do  well  to  go  to  bed  early,  or  remain  in 
a  dark  room. 

11.  Be  careful  to  keep  the  eyes  clean.     Do  not  rub  the 
eyes  with  the  fingers.      Aside  from  consideration  of  rules  of 
etiquette,  there  is  danger  of  introducing  foreign  matter  that 
may  be  very  harmful.      It  is  very  desirable  that  each  person 
have  his  individual  face  towel.     By  not  observing  this  rule, 
certain  contagious  diseases  of  the  eyes  often  spread  rapidly. 

12.  If  there  is  any  continuous  trouble  with  the  eyes,  con- 
sult a  reliable  oculist.      Many  persons  injure  the  eyes  by  not 
wearing  suitable  glasses.     On  the   other  hand,  do  not  buy 
glasses  of  peddlers  nor  of  any  but  reliable  specialists.     One 


316 


in-:  .{RING. 


may  ruin  the  eyes  by  wearing  glasses  when  they  are  not 
needed.     Sight  is  priceless. 

The  Sense  of  Hearing.  —  The  ear  passages  are  inclosed 
by  the  hard  bones  of  the  head.  The  ear  is,  in  consequence, 
difficult  to  dissect.  It  is  very  desirable  to  have  a  model  of 
the  ear,  and  a  good  model  may  be  bought  for  less  than  ten 
dollars.  The  ear  may  be  dissected  in  a  cat  or  rabbit  by  fol- 


Stirrup  Anvil 


Semicircular  Canals 


PHARYNX 


Fig.  93.    Diagram  of  the  Ear. 


lowing  the  accompanying  description.     It  will  take  time  and 
patience  to  trace  all  the  parts. 

The  ear  is  a  much  more  complicated  organ  than  would 
naturally  be  supposed.  The  parts  of  the  ear  are  the  External, 
Middle,  and  Internal  ear.  The  external  ear  gathers  the  sound- 
waves and  directs  them  into  the  opening  of  the  ear,  but  the 
loss  of  the  external  ear  does  not  seriously  interfere  with  hear- 
ing. The  hole  leading  inward  from  the  ear  extends  a  little 


EQUILIBRIUM  SENSE.  317 

more  than  an  inch,  and  is  then  completely  shut  off  from  the 
cavities  beyond  by  a  thin  membranous  partition,  the  Tympanic 
Membrane  or  Drum-skin.  The  skin  of  the  ear  dips  into  and 
lines  the  external  tube,  and  continues  as  a  very  thin  layer  over 
the  membrane  of  the  tympanum.  The  Auditory  Meatus,  as 
this  passageway  is  called,  is  guarded  by  hairs,  and  is  further 
protected  by  wax  secreted  by  glands  of  the  lining.  Beyond 
the  membrane  of  the  tympanum  is  a  cavity  called  the  middle 
ear.  Extending  across  the  cavity  of  the  middle  ear  is  a  chain 
of  very  small  bones,  the  Hammer,  Anvil,  and  Stirrup,  the  ham- 
mer being  attached  to  the  inner  surface  of  the  membrane  of 
the  tympanum,  and  the  stirrup  being  fastened  by  its  base 
to  the  wall  of  the  internal  ear.  The  middle  ear  communi- 
cates with  the  back  part  of  the  mouth  (pharnyx)  by  means  of 
a  narrow  tube  called  the  Eustachian  Tube.  This  tube  is  prob- 
ably closed  most  of  the  time,  but  opens  when  we  swallow. 

The  internal  ear  consists  of  several  complicated  cavities 
and  tubes  which  contain  a  liquid  in  which  rest  the  nerves. 
The  principal  cavity  is  the  Cochlea,  or  snail-shell  cavity,  in 
which  the  nerve  endings  are  connected  with  an  exceedingly 
complicated  apparatus. 

Sound-waves  set  the  drum-skin  or  membrane  of  the  tym- 
panum in  vibration ;  the  vibrations  are  conveyed  by  the  chain 
of  bones  across  the  middle  ear  to  the  liquid  of  the  inner  ear. 
Through  the  complicated  apparatus  of  the  snail-shell  the 
vibrations  of  the  liquid  are  made  to  start  nerve  impulses  in 
the  fibers  of  the  auditory  nerve,  and  when  these  nerve  impulses 
are  rightly  received  and  interpreted  by  the  brain,  we  have  a 
sensation  called  Sound. 

The  Equilibrium  Sense.  —  Probably  most  of  the  senses 
contribute  to  the  maintaining  of  the  equilibrium  of  the  body 
by  giving  information  as  to  position,  motion,  etc.,  especially 
sight  and  the  muscular  sense. 


318  CARE  OF  THE  EAR. 

Only  that  part  of  the  auditory  nerve  which  is  distributed 
in  the  "  snail-shell "  of  the  ear  is  now  supposed  to  have  to  do 
with  hearing.  It  is  no  longer  believed  that  the  Semicircular 
Canals  are  concerned  with  the  process  of  hearing.  There 
seems  to  be  good  evidence  that  the  semicircular  canals  inform 
us  as  to  changes  of  the  position  of  the  body,  and  they  are 
regarded  as  the  seat  of  an  "  equilibrium,  sense."  The  fact 
that  one  of  these  canals  is  horizontal,  and  that  the  two  verti- 
cal canals  are  at  right  angles  to  each  other,  strengthens  this 
belief.  It  is  thought  that  each  of  these  canals  detects  move- 
ments in  its  own  plane.  The  experiment  has  been  made  of 
placing  a  man  on  a  table  that  turned  easily;  with  the  eyes 
shut  the  subject  could  usually  detect  fairly  well  the  changes 
of  position  from  rotation  of  the  table.  What  is  known  on  the 
subject  comes  partly  from  observation  in  cases  where  these 
parts  are  diseased  (which,  in  itself,  does  not  cause  loss  of 
hearing),  and  by  operating  on  lower  animals ;  in  both  of  these 
lines  of  observation  injury  to  these  parts  appears  to  be  fol- 
lowed by  dizziness,  loss  of  power  to  maintain  equilibrium,  etc. 

The  Care  of  the  Ear.  —  In  cleaning  the  ear  no  hard 
substance  should  be  used ;  even  the  finger-nail  is  likely  to 
do  harm.  A  moistened  cloth  should  be  used.  If  this  is 
not  sufficient,  a  physician  should  be  consulted. 

In  washing  the  ear  it  should  be  thoroughly  dried  before 
being  exposed  to  a  wind,  especially  a  cold  wind.  The  rapid 
evaporation  may  cool  the  parts  so  rapidly  as  to  cause  trouble. 
It  is  not  well  to  stuff  the  ears  with  cotton.  If  there  is  any 
trouble  with  the  hearing,  of  course  a  physician  should  be  con- 
sulted without  delay. 

The  existence  of  an  organ  of  hearing  implies  the  existence 
of  what  ?  Why  have  we  these  organs  of  hearing  ?  Is  it 
merely  a  means  of  protection  ?  Is  it  that  we  may  enjoy  the 
music  of  nature,  such  as  the  songs  of  birds  ?  Is  there  not 


HEARING.  319 

one  sound  that  makes  sweeter  music  than  the  most  gifted  of 
feathered  songsters,  surpassing  all  the  instruments  of  man's 
device,  even  the  violin,  with  its  almost  human  flexibility  and 
range  of  expression  ? 

What  sound  communicates  to  us  the  most  of  thought  and 
sympathy  ? 

What  sound  was  it  Robinson  Crusoe,  in  his  dreary  soli- 
tude, most  longed  to  hear? 

READING.  — Physiology  of  the  Special  Senses ,  M'Kendrick  and 
Snodgrass  ;  The  Senses  of  Man,  Bernstein. 


CHAPTER   X. 

THE   VOICE. 

THE  delicate  mechanism  and  capabilities  of  the  ear  are 
fully  matched  by  the  fine  adjustment  and  range  of  the  voice. 
The  organ  of  the  voice  is  well  worthy  of  study,  if  we  look  at 
it  merely  as  a  most  ingenious  contrivance,  to  say  nothing  of 
its  importance  to  us  as  a  means  of  expressing  thought. 

But  to  understand  the  mechanism,  it  is  necessary  to  ex- 
amine the  structure  itself,  for  no  mere  description  can  make 
clear  its  parts  and  their  relations. 

We  can  learn  a  little  from  the  observation  of  our  own 
mouths  and  throats.  The  projection  of  the  throat  known  as 
"Adam's  Apple"  is  one  angle  of  the  Thyroid  cartilage.  A 
ridge  may  be  felt  running  downward  from  the  projecting 
angle.  Above  the  Adam's  apple  a  depression  may  be  felt. 
Press  the  tip  of  the  finger  lightly  into  this  depression  and 
perform  the  act  of  swallowing.  It  will  be  noted  that  the 
Adam's  apple  is  drawn  upward  and  closer  to  the  bone  above 
the  depression.  This  bone  is  the  Hyoid  bone  ;  it  is  connected 
with  the  larynx  below  the  base  of  the  tongue.  Below  the 
thyroid  cartilage  another  cartilage  may  be  felt,  the  Cricoid 
cartilage.  Below  this  is  the  windpipe  with  its  rings  of  car- 
tilage. The  general  form  of  the  whole  larynx  may  be  felt  in 
a  person  not  overburdened  with  fat. 

By  depressing  the  tongue  and  looking  into  the  mouth  the 
tip  of  the  epiglottis  may  possibly  be  seen  at  the  base  of  the 
tongue.  Beyond  these  points  we  cannot  learn  much  without 
dissection.  A  small  mirror  set  oblique!}-  on  a  handle  (like 

320 


DISSECTION    OF    LARYNX.  321 

those  used  by  dentists)  may  be  inserted  through  the  mouth  so 
that  the  larynx  can  be  seen  from  above.  But  the  meaning  of 
what  would  be  thus  seen  would  not  be  very  clear  without  a 
careful  dissection  of  the  larynx. 

The  Larynx  of  the  Calf.  —  1.  The  front  of  the  larynx  is 
readily  distinguished  by  the  projection  of  cartilage  known  as 
the  Adam's  Apple. 

2.  Along  the  back  of  the  larynx  runs  a  thick  muscular 
tube,  the  Gullet,  with  a  whitish  lining,  the  mucous  membrane. 

3.  Trim  away  the  muscles  and  other  tissues  from  the  front 
and   sides   of  the   larynx.      The  large  cartilage   forming  the 
greater  part  of  the  front  of  the  larynx  is  the  Thyroid  Car- 
tilage. 

4.  Observe  the  band  of  muscles  attached  to  either  side  of 
the  thyroid  cartilage  and  passing  horizontally  back  around  the 
esophagus. 

Cut  away  this  muscle  as  completely  as  possible,  and  entirely 
remove  the  gullet.  Note  that  the  whitish  or  yellowish  Mucous 
Membrane  which  lines  the  gullet  is  continuous  with  the  lining 
of  the  larynx.  Study  now  more  fully  the  shape  of  the  thy- 
roid cartilage. 

5.  Back  of  the  upper  part  of  the  thyroid  cartilage,  cover- 
ing the  upper  end  of  the  larynx,  is  the  arched  Epiglottis.     Feel 
of  it  to  learn  its  consistency.     Press  it  upward  and  forward, 
then  downward  and  backward;   observe  that  it  now  covers 
the  entrance  to  the  larynx  ;  note  the  position  it  takes  when 
released. 

.  6.  Just  back  of  the  upper  angle  of  the  thyroid  cartilage 
find  a  muscle  connected  with  the  base  of  the  epiglottis  ;  pull 
this  muscle  to  determine  what  effect  its  shortening  produces 
on  the  epiglottis. 

7.  Under  the  thyroid  cartilage  in  front  observe  a  narrow 
ring  of  cartilage  not  much  wider  than  one  of  the  rings  of  the 


322  DISSECTION    OF    LARYNX. 

trachea.     Move  this  up  and  down  to  prove  that  it  is  distinct 
from  the  thyroid.     This  is  the  Cricoid  Cartilage. 

8.  Observe  the  sheet  of  muscle  passing  from  the  cricoid  to 
the  thyroid.     Again  move  the  cricoid  toward  and  from  the 
thyroid  ;  what  does  this  muscle  do  ?     Cut  away  this  muscle 
from  one  side,  and  see  that  the  cricoid  cartilage  widens  as  it 
passes  backward.     How  are  the  cricoid  and  thyroid  hinged 
together  ? 

9.  Projecting  upward  and  backward  from  the  top  of  the 
larynx  are  two  curved  yellowish  cartilages,  the  Arytenoid  Car- 
tilages.    Move  them  about  to  see  that  they  are  movable,  and 
that  they  rest  on  the  upper  edge  of  the  back  part  of  the 
cricoid  cartilage. 

10.  Move  the  arytenoid  cartilages  backward  and  forward, 
meanwhile  watching  the  inside  of  the  larnyx  from  its  lower 
opening.     The  projecting  ridges,  which  meet  just  back  of  the 
Adam's  apple,  are  the  Vocal  Cords.     What  effect  is  produced 
on  the  vocal  cords  by  the  movements  of  the  arytenoid  car- 
tilages ? 

11.  Observe  the  connection  of  the  thyroid  cartilage  with 
the  cricoid  by  means  of  a  downward  projection  of  the  former. 
Cut  away  all  of  this  half  of  the  thyroid  cartilage.     Notice  the 
slender  Hyoid  Bone  loosely  connected  with  vthe  upper  horn  of 
the  thyroid. 

12.  Examine  now  the  muscles  which  move  the  arytenoid 
cartilages. 

(a)  On  each  side  of  the  posterior  surface  of  the  cricoid  is 
a  muscle  passing  upward  to  be  attached  to  the  corresponding 
arytenoid ;  this  is  the  Posterior  Crico-arytenoid  Muscle.     Dis- 
sect it  loose  from  the  cricoid  at  its  origin  below.     By  pulling, 
determine  its  action  on  the  arytenoid,  and  through  the  aryte- 
noid on  the  vocal  cord. 

(b)  Arising  from  the  upper  edge  of  the  side  of  the  cricoid 


THE    LARYNX.  323 

cartilage,  and  passing  upward  and  backward  to  the  arytenoid, 
is  the  Lateral  Oico-arytenoid  Muscle;  cut  away  at  its  origin 
close  to  the  cricoid,  and  demonstrate  its  action  on  the  aryte- 
noid cartilage  and  vocal  cord. 

(c)  A  broad  muscle  arising  along  the  whole  length  of  the 
angle  of  the  thyroid,  whose  fibers  converge  to  the  arytenoid 
cartilage.     This  is  the  Thyro-arytenoid  Muscle ;  cut  it  across 
near  its  origin,  dissect  it  loose,  and  by  pulling  it  toward  its 
origin  prove  its  action. 

(d)  On  the  posterior  surface  of  the  arytenoids  is  the  small 
Arytenoid  Muscle. 

13.  Cut  between  the  arytenoid  cartilages  and  remove  one 
of  them.     Examine  the  joint  between  the  arytenoid  and  cri- 
coid.     Note  the  synovia  lubricating  the  joint. 

Trim  away  the  muscle  from  the  arytenoid  cartilage  and 
study  its  shape  more  fully.  Fit  it  again  to  its  place,  and 
recall  the  motions  given  by  each  muscle. 

14.  Now  examine  the  arytenoid  cartilage   and  the  vocal 
cord  of  the  opposite  side  ;   move  the  arytenoid  back  and  forth, 
watching  the  vocal  cord. 

15.  Remove   the    epiglottis,  and    cut   into   it   to   see   its 
structure. 

16.  Dissect  away  the  parts  of  the  other  side  from  the  in- 
side, reviewing  the  above  points. 

By  examining  the  larynx  we  see  that  its  cartilages  are  con- 
nected with  each  other  by  ligaments  which  allow  considerable 
freedom  of  motion  ;  that  they  are  also  connected  by  muscles 
which  move  them  one  upon  another.  The  range  of  movement 
of  the  arytenoid  cartilages  and  the  muscular  control  of  these 
cartilages  is  of  special  interest,  for  we  see  that  the  vocal 
cords,  so-called,  are  attached  to  these  cartilages,  and  that  the 
chief  variations  of  the  voice  are  thereby  regulated. 

The  vocal  cords  are  badly  named.     They  are  seen  to  be 


324 


THE    LARYNX. 


mere  ridges  projecting  from  the  sides  of  the  larynx.  Under 
the  covering  of  mucous  membrane  are  ligaments  and  muscles 
that  may  be  stretched  to  various  degrees  and  placed  in  differ- 
ent positions,  according  to  the  sound  that  is  to  be  produced. 

While  we  are  quietly  breathing,  the  vocal  cords,  or  bands, 
lie  back,  like  low  ridges,  against  the  side  of  the  larynx,  and 
offer  nearly  the  whole  channel  of  the  larynx  for  the  free  pas- 
sage of  air  for  breathing  purposes.  But  when  we  wish  to 


Epiglottis 
Base  of  Tongue 

Hyoid  Bone 

False  Vocal  Cord 

Ventricle 
Vocal  Cord 


Cartilage 


~         Trachea 


FROM    RIGHT   TO    LEFT  MEDIAN 

Fig.  94.     Longitudinal  Sections  of  the  Larynx. 

produce  vocal  sound,  the  vocal  cords  are  made  to  stand  out 
farther  from  the  side  walls,  and  interfere  with  the  free  pas- 
sage of  the  air.  In  examining  the  larynx  it  is  seen  that  the 
vocal  cords  are  attached  close  to  each  other  in  front,  but  that 
at  the  back  of  the  larynx  they  diverge  widely  (in  the  position 
of  rest),  forming  a  letter  V,  with  the  angle  of  the  V  in  front, 
just  back  of  Adam's  apple.  t(  When  changes  in  the  voice  or 
in  breathing  are  being  made,  the  white  glistening  vocal  cords 
may  be  seen  to  come  together  or  to  go  apart  like  the  blades  of 


VOCAL    COEDS.  325 

a  pair  of  scissors."  In  a  high  note  the  cords  are  close  together 
and  nearly  parallel.  As  the  air  is  forced  past  the  approxi- 
mated edges  of  the  vocal  cords,  they  are  set  in  vibration,  and 
produce  the  sound  called  the  voice.  The  principle  of  the 
action  of  the  vocal  cords  can  be  illustrated  by  the  common 
toy  known  as  the  the  squeaking  balloon,  or  "squawker." 
Here  the  air  is  driven  out  past  a  band  of  rubber  stretched 
across  the  inner  end  of  the  tube.  If  instead  of  one  band  with 
both  edges  free,  we  were  to  tie  on  the  inner  end  of  the  tube 
two  bands  of  rubber,  each  covering  the  outer  edge  of  the  tube, 


Epiglottis 
False  Vocal  Cords  — 

True  Vocal   Cords 


Glottis  Narrowed,  High  Note  Glottis  Wider,  Quiet  Breathing 

Fig.  95.     The  Larynx,  as  Seen  by  Means  of  the  Laryngoscope,  in  Different 
Conditions  of  the  Glottis. 


leaving  the  inner  edge  of  the  rubber  free,  and  with  the  two 
bands  touching  at  one  end  and  considerably  separated  at  the 
other  end,  we  would  have  a  pretty  fair  resemblance  to  the 
larynx.  As  in  many  musical  instruments,  the  vibrations  of 
the  membrane  itself  alone  would  be  too  feeble  to  have  much 
effect.  In  the  violin,  piano,  drum/ etc.,  the  vibrations  are  re- 
enforced  by  the  vibration  of  a  body  of  air  contained  within. 
So  here  the  vibrations  of  the  cords  are  reenforced  and  modi- 
fied by  the  air  spaces  above.  The  loudness  of  the  voice  de- 
pends on  the  force  with  which  the  air  is  driven  past  the  cords, 
together  with  the  size  and  condition  of  the  cords  themselves. , 
Pitch  depends  on  the  rapidity  of  the  vibrations,  which  is  de- 


326  VOICE  AND  SPEECH. 

termined  by  the  length  of  the  cords  and  their  tension.  Other 
things  being  equal,  the  size  of  the  larynx  would  determine  the 
pitch. 

The  larynx  by  itself  produces  vocal  sound  merely.  In 
speech  the  sounds  produced  in  the  larynx  are  much  modified 
by  the  lips,  tongue,  teeth,  cheeks,  etc. 

We  have  voice  as  soon  as  born,  but  we  only  gradually 
acquire  the  power  of  speech.  Mammals,  birds,  and  some  of 
the  lower  vertebrates  have  voices,  but  they  have  not  speech. 
This  distinguishes  man  from  the  animals  below  him,  though 
perhaps  some  of  the  higher  apes  have  it  in  a  slight  degree. 
Dogs  can  express  their  wants  by  barking,  growling,  snarling, 
etc.,  but  it  is  mostly  by  their  tone,  with  their  attitudes,  and 
a  slight  facial  expression  (as  in  snarling). 

By  various  positions  of  the  tongue  and  organs  of  the 
throat  we  make  the  different  vowel  sounds.  In  the  conso- 
nants we  more  or  less  shut  off  (for  the  time)  the  passage 
of  air,  and  so  stop,  or  modify,  the  sound.  This  is  hardly 
the  place  to  study  and  analyze  the  sounds  of  our  spoken 
language,  yet  it  may  be  found  profitable  to  watch  the  differ- 
ent organs  as  each  sound  is  produced;  for  when  the  structure 
and  relation  of  the  different  parts  concerned  in  the  pro- 
duction of  these  sounds  are  better  known,  the  definitions 
and  statements  of  the  books  will  be  much  more  fully  under- 
stood. 

Since  no  two  throats  are  exactly  alike,  no  two  voices 
sound  just  the  same.  The  size  and  shape  of  the  pharynx, 
the  shapes  and  positions  of  the  teeth,  lips,  the  condition  of 
the  mucous  membrane  of  the  passages  generally,  all  affect  the 
sound,  and  give  it  its  "  quality  "  by  which  we  distinguish  one 
voice  from  another,  even  if  they  are  in  the  same  pitch  and 
have  the  same  degree  of  loudness. 

If  the  mucous  membrane  covering  the  vocal  cords  is  in- 


VOICE  AND  SPEECH.  327 

flamed,  or  covered  with  too  much  mucus,  hoarseness  is  likely 
to  result. 

As  in  the  animal  we  have  voice  without  speech,  so  in 
whispering  we  have  speech  without  voice ;  that  is,  there  is 
no  true  vocalization.  The  organs  of  speech  so  modify  the 
aspiration  as  to  produce  speech.  There  is  no  true  voice. 

The  voice  and  speech  are  very  susceptible  of  culture, 
and  nearly  all  voices  may  improve  by  proper  cultivation. 
A  cultivated  voice  and  careful,  distinct  speech  are  very  desi- 
rable accomplishments,  and  are  not  nearly  so  common  as  they 
ought  to  be.  We  learn  (or  think  we  do)  to  talk  very  early ; 
and  many  individuals  never  give  the  matter  any  considera- 
tion, but  inflict  their  harshness  and  crudity  of  utterance  on 
people  who  cannot  always  defend  themselves  even  by  escape. 
Many  a  public  speaker  or  teacher,  who  has  fine  thought,  can 
secure  but  few  listeners  because  of  an  unpleasant  voice.  He 
is  limited  to  writing  in  his  attempt  to  disseminate  his  ideas. 
We  delight  in  fine  singing,  and  many  strive  to  cultivate  this 
art ;  but  not  so  many  try  to  learn  to  talk  so  that  it  is  a 
pleasure  to  hear  the  spoken  sound. 

READING.  —  The  Throat  and  the  Voice,  Cohen. 


CHAPTER    XL 

ACCIDENTS. 
WHAT    TO    DO    TILL   THE    DOCTOR    COMES. 

How  to  Stop  Flow  of  Blood  from  Wounds.  —  In  case 
of  bleeding  from  an  artery  the  blood  comes  in  jets.  Pressure 
should  be  applied  between  the  cut  and  the  heart.  To  know 
where  to  apply  the  pressure,  study  of  the  course  of  the  main 
arteries  should  be  made.  By  studying  Fig.  22  it  will  be 
seen  that  the  arteries  to  the  arms  pass  down  the  inside  of  the 
upper  arm.  Here  they  come  near  the  surface.  At  the  elbow 
the  artery  is  near  the  skin  in  the  angle  of  the  elbow.  The 
artery  which  makes  the  pulse  at  the  wrist  is  well  known. 
By  putting  a  baseball  under  the  armpit,  and  pressing  the  arm 
down  firmly,  the  artery  may  be  compressed. 

In  case  of  a  deep  cut  in  the  lower  part  of  the  upper  arm, 
a  handkerchief  should  have  a  knot  tied  in  it,  and  the  knot 
placed  over  the  artery  ;  that  is,  on  the  inside  of  the  arm  just 
below  the  armpit.  Pass  the  handkerchief  around  the  arm 
and  tie  it  loosely.  Then  run  a  stick  through  it,  and  twist  till 
the  knot  is  drawn  tightly  against  the  artery.  Instead  of  a 
knot  a  potato,  or  anything  else  to  make  a  firm  lump,  may  be 
used.  If  the  forearm  is  cut,  the  pressure  should  be  applied 
in  the  angle  of  the  elbow.  (See  Frontispiece.) 

In  studying  the  pulse,  we  found  the  Carotid  artery  in  the 
neck.  If  a  deep  cut  has  been  made  in  the  upper  part  of  the 
neck,  it  might  be  possible  to  stop  the  flow  by  compressing 
the  artery  lower  down  the  neck.  The  Femoral  artery  comes 

328 


TREATMENT  OF  HEMORRHAGE.         329 

near  the  surface  in  the  groin.  Pressure  may  be  applied  here 
in  the  same  way  to  stop  bleeding  from  a  cut  farther  down 
the  thigh.  In  the  angle  back  of  the  knee,  pressure  may  com- 
press the  artery  supplying  the  leg.  Nosebleed  may  some- 
times be  stopped  by  pressing  firmly  at  the  base  of  the  nose. 

In  case  of  severe  wounds,  pressure  should  be  applied  im- 
mediately to  the  wound.  Sometimes  it  is  well  to  make  a 
plug  of  cloth,  and  press  upon  the  cut. 

In  case  of  bleeding  from  veins,  holding  the  part  up  may 
check  the  flow.  If  necessary  to  apply  pressure,  it  should  be 
beyond  the  cut,  instead  of  between  it  and  the  heart  as  in  the 
case  of  the  artery. 

Blood  from  the  lungs  is  bright,  frothy,  and  salty;  from 
the  stomach  is  dark  and  sour.  In  case  of  bleeding  from  the 
lungs  or  stomach,  let  the  person  rest  quietly  on  a  lounge  or 
easy-chair.  Give  him  some  bits  of  ice  to  swallow. 

Bleeding  from  the  Nose.  —  Do  not  lean  forward,  as  this 
position  aids  the  flow.  Sit  up,  and  hold  up  the  head,  and 
hold  a  cloth  under  the  nose.  Apply  cold  water  or  ice  to  the 
nose  and  to  the  back  of  the  neck.  If  this  does  not  stop  it, 
inject  cold  water,  with  a  little  salt  or  soda  in  it,  into  the 
nose.  Often  the  flow  may  be  stopped  by  pressing  firmly  on 
the  upper  lip  at  the  sides  of  the  nose.  If  these  attempts 
fail,  a  long  strip  of  cloth  may  be  used  to  plug  the  nostril, 
pushing  the  cloth  in  a  little  at  a  time,  and  leaving  the  ends 
so  it  can  be  pulled  out ;  this  should  not  be  done  till  a  long 
time  after  the  flow  is  checked,  as  it  may  start  the  bleeding 
afresh.  After  an  attack  of  this  kind  avoid  blowing  the  nose, 
as  this  often  starts  bleeding  again. 

Burns.  —  Plunge  the  burned  part  into  cold  water.  As 
soon  as  possible  apply  a  solution  of  cooking  soda  (bicarbonate 
of  soda),  a  tablespoonf ul  to  a  teacup  or  tumbler  of  water ;  or 
lay  a  wet  cloth  on  the  burned  part  and  put  the  soda  on  the 


330  TREATMENT  OF  FAINTING. 

cloth.  Afterwards  apply  vaseline,  and  renew  the  vaseline  till 
the  wound  is  healed. 

A  mixture  of  equal  parts  of  sweet  oil  and  limewater  makes 
a  good  liniment  for  dressing  burns.  Flour  thickly  spread 
over  the  burn  is  good,  but  probably  where  the  flour  is  avail- 
able, soda  can  also  be  had.  Vaseline  should  be  freely  used  on 
burns. 

If  the  clothing  takes  fire,  there  is  added  to  the  danger  of 
burning  the  body,  the  further  risk  of  inhaling  the  flame  and 
heated  air.  It  is  best  to  lie  down,  and  roll  and  wrap  the  body 
in  any  cloths  at  hand,  —  rugs,  shawls,  etc.  Running  serves  to 
fan  the  flames.  Hence,  if  a  person  whose  clothing  is  on  fire 
is  seen  to  be  thoroughly  frightened,  and  to  have  lost  presence 
of  mind  and  to  be  starting  to  run,  the  best  thing  to  do  usually 
is  to  grasp  and  try  to  throw  him  to  the  ground,  putting  a 
wrap  of  some  kind  abound  the  body  at  the  same  time  if  pos- 
sible. Rolling  on  the  ground  or  floor  in  itself  would  very 
likely  put  out  a  small  flame. 

Soda  and  dilute  ammonia  are  good  for  bee  stings,  etc. 

Fainting. — Lay  the  body  flat  on  the  back.  Keep  the 
crowd  away.  Give  plenty  of  fresh  air.  Loosen  the  clothing 
about  the  neck  and  waist.  Sprinkle  cold  water  on  the  face 
(do  not  drench  the  body  with  a  quantity  of  water).  Apply 
smelling-salts  (ammonia)  to  the  nostrils  ;  rub  the  limbs  toward 
the  body.  If  these  remedies  do  not  soon  restore  consciousness, 
send  for  a  physician.  A  faint  is  not  usually  a  serious  matter. 
Bad  ventilation,  disagreeable  odors,  or  even  the  oversweet 
odors  of  such  flowers  as  the  tuberose,  may  cause  fainting. 

Broken  Bones.  —  Keep  the  patient  as  quiet  as  possible 
till  the  physician  arrives.  There  need  be  no  anxiety  if  the 
physician  is  delayed,  as  ordinarily  no  harm  comes  from  wait- 
ing. If  there  is  inflammation,  cold  water  may  be  applied. 
Cooling  applications  are  desirable  in  case  of  severe  bruises. 


RESUSCITATION  FROM  DROWNING. 


331 


If  it  is  necessary  to  carry  the  patient,  lay  him  on  a  board,  or  at 
least  keep  the  injured  part  as  quiet  as  possible  j  a  cane  or  um- 
brella may  be  tied  alongside  a  leg,  and  supported  by  a  pillow 
or  a  coat.  Sometimes  the  sharp  ends  of  the  bones  may  cut  the 
flesh  or  even  blood  tubes. 

Sunstroke.  —  Lay  the  patient  in  the  shade,  and  pour  cold 
water  over  the  head. 

TREATMENT   OF    THE   DROWNED 
(As  given  by  the  Michigan  Hoard  of  Health.) 

Rule  1.    Remove  all  obstructions  to  breathing.     Instantly 
loosen  or  cut  apart  all  neck  and  waist  bands  j  turn  the  patient 


Fig.  96.    Resuscitation  from  Drowning. 
Position  1. 


on  his  face,  with  the  head  down  hill ;  stand  astride  the  hips 
with  your  face  toward  his.  head,  and,  locking  your  fingers 


332 


RESUSCITATION  FROM  DROWNING 


together  under  his  belly,  raise  the  body  as  high  as  you  can 
without  lifting  the  forehead  off  the  ground  (Fig.  96,  Position 
1),  and  give  the  body  a  smart  jerk  to  remove  mucus  from  the 
throat  and  water  from  the  windpipe;  hold  the  body  sus- 
pended long  enough  to  count  slowly  One,  Two,  Three,  Four, 
Five,  repeating  the  jerk  more  gently  two  or  three  times. 


Fig.  97.    Resuscitation  from  Drowning. 
(Position  2.) 

Rule  2.  Place  the  patient  on  the  ground  face  downward, 
and,  maintaining  all  the  while  your  position  astride  the  body, 
grasp  the  points  of  the  shoulders  by  the  clothing,  or,  if  the 
body  is  naked,  thrust  your  fingers  into  the  armpits,  clasping 
your  thumbs  over  the  points  of  the  shoulders,  and  raise  the 
chest  as  high  as  you  can  (Fig.  97,  Position  2)  without  lifting 
the  head  quite  off  the  ground,  and  hold  it  long  enough  to 
count  slowly  One,  Two,  Three.  Replace  him  on  the  ground, 


RESUSCITATION  FROM  DROWNING. 


333 


with  his  forehead  on  his  flexed  arm,  the  neck  straightened 
out,  and  the  mouth  and  nose  free.  Place  your  elbows  against 
your  knees,  and  your  hands  upon  the  sides  of  his  chest  (Fig. 
98,  Position  3)  over  the  lower  ribs,  and  press  downward  and  in- 
ward with  increasing  force  long  enough  to  count  slowly  One, 
Two.  Then  suddenly  let  go,  grasp  the  shoulders  as  before, 


Fig.  98.    Resuscitation  from  Drowning. 
(Position  3.) 

and  raise  the  chest  (Position  2),  then  press  upon  the  ribs,  etc. 
(Position  3).  These  alternate  movements  should  be  repeated 
ten  or  fifteen  times  a  minute  for  an  hour  at  least,  unless 
breathing  is  restored  sooner.  Use  the  same  regularity  as  in 
natural  breathing. 

Eule  3.  After  breathing  has  commenced,  Restore  the  Ani- 
mal Heat.  Wrap  him  in  warm  blankets,  apply  bottles  of  hot 
water,  hot  bricks,  or  anything  to  restore  heat.  Warm  the 


334  RESUSCITATION  FROM  DROWNING. 

head  nearly  as  fast  as  the  body  lest  convulsions  come  on. 
Rubbing  the  body  with  warm  cloths  or  the  hand,  and  slap- 
ping the  fleshy  parts,  may  assist  to  restore  warmth,  and  the 
breathing  also.  If  the  patient  can  surely  swallow,  give  hot 
coffee,  tea,  milk,  or  a  little  hot  sling.  Give  spirits  sparingly, 
lest  they  produce  depression.  Place  the  patient  in  a  warm 
bed,  and  give  him  plenty  of  fresh  air ;  keep  him  quiet. 

BEWARE ! 

Avoid  Delay.  A  moment  may  turn  the  scale  for  life  or 
death.  Dry  ground,  shelter,  warmth,  stimulants,  etc.,  at  this 
moment  are  nothing — Artificial  breathing  is  everything  —  is 
the  One  Remedy  —  all  others  are  secondary. 

Do  not  stop  to  remove  wet  clothing.  Precious  time  is 
wasted,  and  the  patient  may  be  fatally  chilled  by  the  expo- 
sure of  the  naked  body,  even  in  summer. 

Give  all  your  attention  and  effort  to  restore  breathing  by 
forcing  air  into,  and  out  of,  the  lungs.  If  the  breathing  has 
just  ceased,  a  smart  slap  on  the  face,  or  a  vigorous  twist  of 
the  hair  will  sometimes  start  it  again,  and  may  be  tried  inci- 
dentally. 

Before  natural  breathing  is  fully  restored,  do  not  let  the 
patient  lie  on  his  back  unless  some  person  holds  his  tongue 
forward.  The  tongue  by  falling  backward  may  close  the  wind- 
pipe, and  cause  fatal  choking. 

Prevent  friends  from  crowding  around  the  patient  and  ex- 
cluding the  fresh  air ;  also  from  trying  to  give  stimulants 
before  the  patient  can  swallow.  The  first  causes  suffocation ; 
the  second,  fatal  choking. 

Do  not  give  up  too  soon :  you  are  working  for  life.  Any 
time  within  two  hours  you  may  be  on  the  very  threshold  of 
success  without  there  being  any  sign  of  it. 


SUFFOCATION    IN    WELLS.  335 

(The  above,  with  figures,  is  taken  from  Lincoln's  Hygienic 
Physiology.) 

Of  course  persons  who  cannot  swim  well  ought  not  to  go 
out  in  a  boat  without  taking  along  some  sort  of  a  float  that 
may  serve  as  a  life-preserver.  Some  of  the  rubber  cushions 
serve  well  for  this. 

In  case  an  ordinary  rowboat  is  overturned,  one  should  not 
attempt  to  climb  into  it  or  upon  it.  It  takes  very  little  to  float 
a  person  in  water,  as  the  body  is  only  a  little  heavier  than 
water ;  in  fact,  if  a  person  fills  the  lungs  and  lies  back  in.  the 
water,  his  face  and  nose  will  keep  above  water,  and  a  person 
(at  any  rate  without  clothing)  can  float  in  this  way  for  some 
time,  if  he  breathes  lightly.  The  trouble  is  that  the  person 
tries  to  lift  the  whole  head  out  of  the  water.  The  dog,  and 
such  animals,  when  swimming,  have  little  out  of  the  water 
but  the  tip  of  the  nose  and  a  little  of  the  top  of  the  head.  If 
we  could  learn  something  from  them  it  would  be  a  good 
thing.  The  easiest  way  to  float  is  on  the  back.  Few  persons 
have  been  taught  these  facts;  and  most  of  those  who  have 
learned  them  lose  their  presence  of  mind,  and  waste  their 
breath  and  strength  in  wild  and  fruitless  splashing.  If  a 
boat  be  overturned,  those  who  can  swim  should  help  those 
who  cannot  to  get  hold  of  the  edge  of  the  boat,  but  not  permit 
them  to  climb  upon  it.  A  small  plank  will  float  a  person  if 
he  will  not  try  to  lift  much  of  his  body  out  of  the  water. 

Every  father  neglects  his  duty  if  he  does  not  teach  his 
children,  girls  as  well  as  boys,  to  swim  and  to  float.  One 
cool,  trained  person  may  save  the  lives  of  a  whole  boat  load. 

Suffocation  in  Wells.  —  Persons  are  sometimes  suffo- 
cated by  carbon  dioxid  in  wells  and  cisterns.  Before  going 
down  into  a  well  it  is  a  safe  precaution  to  lower  a  lighted 
candle.  If  this  is  extinguished,  a  warning  is  given.  If  a 
second  person  goes  down  after  one  who  has  become  uncon- 


336  POISONS    AND    ANTIDOTES. 

scions,  great  care  must  be  taken  that  two  lives  are  not  lost. 
A  rope  should  be  firmly  tied  about  the  body,  a  hook,  attached 
to  another  rope,  taken  to  catch  into  the  clothing  of  the  first, 
and  the  rescuer  should  be  lowered  quickly  and  brought  up 
immediately.  A  small  rope  or  large  cord  might  be  carried, 
by  pulling  which  the  signal  is  given  to  pull  up. 

In  resuscitating  from  carbon  dioxid  suffocation  use  the  same 
method  as  after  drowning,  except  the  first  part,  which  is  to 
remove  water  from  the  windpipe,  etc. 

Poisons  and  their  Antidotes.  —  Several  of  the  common 
drugs  and  remedies  kept  about  the  house  are  more  or  less  poi- 
sonous. The  proper  antidote  for  each  should  be  known  and 
kept  at  hand.  In.  the  first  place,  all  such  materials  should  be 
kept  locked  up  so  that  they  will  not  be  taken  by  children,  or 
by  mistake,  as  in  the  haste  of  getting  medicine  in  the  night. 
Again,  all  grown  persons  in  the  family  should  be  instructed 
as  to  the  effects  of  each  poison,  and  taught  its  antidote.  As 
soon  as  any  new  poisonous  drug  is  bought,  it  should  be  made 
a  point  to  read  up  about  it,  and  procure  an  antidote.  Every 
one  should  know  that  strychnine  causes  spasms,  that  opium 
brings  on  stupor,  with  contracted  pupils,  etc. 

Treatment  aims  at  three  things,  (1)  to  get  rid  of  the  poison, 
(2)  to  neutralize  what  remains  and  prevent  further  action,  (3) 
to  remedy  the  effects  already  produced. 

1.  The  most  common  Emetic  is  Mustard ;  a  tablespoonful 
in  a  cup  of  warm  water ;  give  half  of  it,  following  with  free 
drinking  of  warm  water,  then  give  the  rest  of  the  mustard. 
Do  not  wait  for  it  to  dissolve,  but  stir  quickly  and  give  at 
once.  Provoke  vomiting  by  tickling  the  throat  with  a  feather 
or  with  the  finger.  If  the  mouth  of  the  patient  cannot 
readily  be  opened,  insert  the  thumbs  inside  the  cheeks  and 
back  of  the  teeth.  If  mustard  is  not  at  hand,  a  strong  solu- 
tion of  table  salt  will  serve.  In  a  few  cases,  such  as  poi- 


POISON    IN    WOUNDS  337 

soning  by   ammonia,   lye,  etc.,   it  is    considered  best   not  to 
administer  an  emetic,  but  to  try  to  neutralize  the  effect. 

2.  To  neutralize    a   poison    this    general    rule    should    be 
known  :    an  alkali   may  be   neutralized   by  an  acid  and  vice 
versa.     For   example,   lye  with   vinegar,   carbolic    acid  with, 
whiting  or  magnesia,  etc.     Some  acids  and  alkalis  are  always 
about  a  house. 

3.  After  any  irritant  poison  some  mild  and  soothing  sub- 
stance  should  be  given,  —  white-of-egg,   milk,   mucilage   and 
water,    flour    and    water,    gruel,    olive    or    castor-oil.      These 
materials    are    partly    for    neutralizing   the    poison,   and    are 
also  soothing  in  their  effect.     If  a  patient  is  drowsy,  some 
stimulant  may  be  given,  as  strong  coffee  (after  opium).     Of 
course  a  physician   should  be  sent  for  immediately,  as  the 
after-treatment  is  of  great  importance. 

The  following  tables  of  "  Poisons,  their  Symptoms,  Anti- 
dotes, and  Treatment,"  are  taken  from  the  excellent  Text- 
book of  Nursing  by  Clara  Weeks-Shaw. 

Wounds  from  Thorns,  Rusty  Nails,  Bites  of  Cats, 
Dogs,  etc.  —  Promote  bleeding  by  rubbing  and  pressing  the 
wound  and  bathing  with  warm  water.  Or  suck  the  wound. 
This  tends  to  remove  any  injurious  matter.  Apply  poultices. 

If  the  animal  is  rabid  (mad),  suck  the  wound  and  cauterize 
quickly.  A  poker  or  nail  heated  red  hot  is  best  for  cauteriz- 
ing. If  one  cannot  do  this  promptly,  get  lunar  caustic  with 
which  to  cauterize ;  strong  acid  or  alkali,  or  a  coal  of  fire,  may 
be  applied  at  once  to  the  wound  ;  the  coal  on  a  cigar  may  be 
used.  Do  not  kill  the  animal  if  there  is  doubt.  Keep  it  con- 
fined, and  if  it  proves  a  false  alarm  much  anxiety  will  be 
saved. 

Snake  Bites.  —  Apply  ligatures  around  the  part  between 
it  and  the  heart.  Suck  the  wound  (there  is  no  danger  in  this 
if  there  are  no  sores  or  cracks  in  the  skin  of  the  mouth ;  venom 


338 


POISONS    AND    ANTIDOTES. 


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POISONS    AND    ANTIDOTES. 


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POISONS  AND   ANTIDOTES. 


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342  CARE  OF  THE  SICK. 

is  not  a  stomach  poison,  though  of  course  it  should  not  be  swal- 
lowed). Then  apply  caustics  or  a  live  coal.  Have  the  patient 
drink  freely  of  whisky  or  brandy.  If  ammonia  water  is  at 
hand,  add  five  teaspoonfuls  to  each  pint  of  liquor. 

Ammonium  carbonate,  ten  per  cent  solution,  is  also  highly 
recommended.  A  teaspoonful  dose  should  be  given  immedi- 
ately, and  repeated  twice  at  intervals  of  ten  minutes. 

Poison  Ivy The  itching  and  discomfort  may  be  relieved 

by  bathing  the  part  in  a  mixture  of  — 

Two  teaspoons  of  carbolic  acid  (pure), 

Two  tablespoons  of  glycerin, 

One  half  pint  of  water  or  rose-water. 

The  Sick-Room.  —  Every  boy  and  girl  ought  to  learn  some- 
thing about  the  care  of  the  sick,  as  any  one  is  likely  to  be 
called  on  to  do  this  kind  of  work.  Good  nursing  is  often 
"  half  the  battle."  In  the  first  place,  the  nurse  should  faith- 
fully follow  the  directions  of  the  physician.  Not  to  do  this 
is  to  set  one's  self  up  as  superior  in  knowledge  to  him ;  and 
this  obedience  should  be  complete  as  to  admission  of  visitors, 
as  well  as  in  administering  medicine,  etc.  The  nurse  often 
yields  to  the  persuasion  of  some  unwise  friend,  "  It  won't  do 
any  harm  for  him  to  see  me." 

The  nurse  should  have  a  quick  sympathy,  and  make  the 
patient  feel  that  all  that  can  be  done  for  his  comfort  will  be 
done ;  yet  this  sympathy  must  not  lead  the  nurse  to  do  any- 
thing for  or  give  anything  to  the  patient  contrary  to  the 
orders  of  the  physician.  The  nurse  should  always  be  cheer- 
ful, even  when  the  patient  is  "  impatient "  arid  annoying  in 
his  demands.  The  patient  is  not  "  himself,"  and  no  attention 
should  be  paid  to  his  unnatural  irritability. 

The  patient  should  have  a  cheerful  room,  but  the  bed 
should  be  so  placed  that  the  light  will  come  not  too  strongly 


CARE  OF  THE  SICK.  343 

into  his  face.  Evidence  of  illness,  such  as  medicine  bottles, 
etc.,  should  be  kept  out  of  sight  so  far  as  possible. 

While  it  is  not  best  to  deceive  the  patient  as  to  his  condi- 
tion, there  should  at  all  times  be  kept  up  an  air  of  cheerfulness 
and  hope.  If  the  physician  can  inspire  with  confidence,  and 
the  nurse  give  unflagging  good  cheer,  the  chances  of  recovery 
are  vastly  improved.  Nothing  sustains  like  Hope. 

Keep  the  air  of  the  room  pure.  Remove  excreta  and  every- 
thing offensive  just  as  soon  as  possible.  Do  not  rely  on  feeling 
as  to  temperature,  but  keep  a  thermometer  in  the  room.  One 
of  the  necessary  characteristics  of  a  good  nurse  is  the  power  of 
imagination.  "  How  would  I  feel,  and  what  would  I  like  to 
have  done  for  me,  if  I  were  in  his  place  ?  "  This  feeling  will 
lead  the  nurse  frequently  to  raise  the  patient's  head  and  turn 
the  pillow  —  the  coolness  of  the  other  side  of  the  pillow  is 
refreshing ;  to  give  sips  of  cool  water  ;  to  see  that  the  patient 
does  not  suffer  for  want  of  a  bath ;  in  giving  a  bath,  to  do  the 
work  thoroughly,  as  a  skillful  barber  carefully  and  thoroughly 
reaches  every  fold  and  crevice  back  of  the  ear,  etc.  In  bathing 
a  weak  person,  only  a  part  of  the  body  should  be  moistened  at 
a  time ;  after  this  part  is  thoroughly  dried,  another  part  may 
be  washed ;  it  is  often  necessary  to  do  all  this  work  under  the 
bed  clothing.  In  changing  the  bed  clothing,  move  the  patient 
to  one  side  of  the  bed,  push  the  clothing  along  close  to  his 
body,  and  place  the  clean  bedding  on  the  other  side ;  then 
move  the  patient  back,  remove  the  soiled  linen,  and  smooth 
out  the  clean.  It  is  often  necessary  to  warm  the  sheets  first ; 
they  should  be  thoroughly  dry. 

Have  the  physician's  directions  written  out  plainly,  as  they 
may  be  forgotten ;  and  if  there  is  a  change  of  nurses  during 
the  night  there  is  less  chance  of  mistake.  Never  let  yourself 
get  drowsy  when  acting  as  nurse.  Get  up  and  walk  about, 
get  a  breath  of  fresh  air,  and  if  inclined  to  be  drowsy  do  not 


344  CARE  OF  TUE  SICK. 

allow  yourself  to  settle  back  in  an  easy-chair.  If  watching  all 
night,  take  a  good  lunch  in  the  middle  of  the  night ;  coffee 
may  help  to  keep  you  awake.  It  is  not  to  be  expected  that 
one  who  has  worked  hard  all  day  out-doors  will  be  likely  to 
keep  awake  all  night.  There  should  be  day  and  night  watch- 
ers, and  one  would  better  not  watch  more  than  six  hours  at  a 
time. 

Do  not  allow  the  room  to  be  swept  with  the  ordinary 
broom.  The  room  should  have  rugs  that  can  be  removed  and 
shaken,  and  the  floor  wiped  with  a  moist  cloth.  If  the  room 
is  carpeted,  it  may  be  swept  with  moist  salt,  tea-grounds  or 
coffee-gounds,  sawdust,  etc.  Any  dusting  should  be  avoided ; 
furniture  may  be  wiped  with  a  damp  cloth. 

In  the  effort  to  be  quiet  many  make  a  mistake  ;  do  not 
whisper,  as  it  disturbs  more  than  talking,  and  also  has  an  air 
of  secrecy  that  rouses  suspicion  in  the  patient.  In  walking 
on  tiptoe,  often  floors  and  stairs  are  made  to  creak  when  they 
would  not  in  ordinary  circumstances.  It  takes  little  reflection 
to  see  that  in  walking  on  tiptoe  one  brings  more  weight  than 
usual  on  a  smaller  part  of  the  floor,  and  is  therefore  more 
likely  to  spring  a  board  in  the  floor ;  it  is  best  (like  the  good 
servant  Baum,  in  Auerbach's  novel  On  the  Heights)  to  walk 
flat-footed.  Wear  an  easy  pair  of  shoes ;  an  old  pair  are  likely 
to  be  quiet.  Kaise  the  head  with  the  hand,  or  bolster  the 
patient  up,  when  giving  drink ;  or  if  the  patient  is  very  weak, 
use  a  rubber  tube,  so  that  he  will  not  have  to  lift  the  head. 
The  nurse  should  know  how  to  prepare  any  food  that  may  be 
needed  during  the  night.  An  oil-stove  or  gas-stove  is  very 
desirable  for  cooking,  or  heating  poultices,  as  an  ordinary  wood 
or  coal  fire  is  likely  to  die  down,  making  it  impossible  for  the 
nurse  to  do  this  work  quickly,  as  is  often  necessary  to  take 
advantage  of  a  favorable  time,  as  when  the  patient  wakens,  etc. 

Most  lamps,  when  turned  low,  give  off  a  disagreeable  gas. 


CA RE  OF  THE  SICK.  345 

It  is  better  to  have  a  very  small  lamp  burning  at  full  height 
than  a  large  one  turned  low ;  sperm  candles  are  recommended. 

It  is  well  for  every  one  to  know  something  about  bandaging, 
preparation  of  food  for  the  sick,  etc.  Space  here  will  not 
allow  further  treatment  of  these  subjects ;  and  the  student  is 
referred  to  treatises  on  the  care  of  the  sick,  of  which  there  are 
several  good  ones  mentioned  at  the  end  of  this  chapter. 

It  is  well  known  that  a  sneeze  may  be  prevented  by  firmly 
pressing  on  the  upper  lip.  This  may  enable  a  nurse  to  keep 
from  waking  a  very  sick  patient  when,  at  a  critical  point,  sleep 
is  almost  a  question  of  life  or  death.  And  it  is  a  convenient 
fact  for  any  one  to  know.  To  prevent  coughing,  there  are 
cough  drops  that  will  relieve  the  tickling  in  the  throat.  It  is 
not  right  for  a  person  who  knows  that  he  has  a  cold  to  disturb 
a  whole  congregation  by  coughing  when,  for  five  cents  and  a 
little  forethought,  he  might  have  prevented  the  annoyance. 

For  Disinfectants  see  Appendix  B. 

In  addition  to  the  list  of  books  on  Accidents,  Emergencies, 
etc.,  already  given,  read  Hand-Book  of  Nursing,  published 
under  the  direction  of  the  Connecticut  Training-School  for 
Nurses,  State  Hospital,  New  Haven,  Conn. ;  Text-Book  of 
Nursing,  Clara  Weeks-Shaw ;  Nursing :  Its  Principles  and 
Practice,  Isabel  Adams  Hampton. 


CHAPTER   XII. 
THE     SKELETON 

OBSERVE  that  the  skeleton  as  a  whole  consists  of  two 
portions,  —  the  Axial  Portion,  consisting  of  a  central  axis,  the 
spinal  column,  to  which  the  head  belongs ;  and  the  Appen- 
dicular  Portion,  the  limbs  and  the  bones  belonging  to  them. 

In  the  skeleton  as  a  whole  observe :  — 

1.  The  skeleton  shows  the  form  of  the  body. 

2.  It  supports  the  softer  tissues. 

3.  It  protects  softer  parts,  as  the  brain  in  the  skull,  the 
spinal  cord  in  the  spinal  column,  the  heart  and  lungs  in  the 
thorax,  etc. 

4.  The  bones  serve  as  levers  in  producing  motion  and  lo- 
comotion. 

The  central  part  of  the  skeleton  is  the  Backbone,  or  Spi- 
nal Column.  As  a  whole,  it  is  a  column,  widening  toward  the 
base,  composed  of  a  series  of  separate  bones  called  Vertebrae. 

Take  a  vertebra  from  the  middle  of  the  spinal  column :  — 

1.  Its  most  solid  part  is  its  body,  or  Centrum. 

2.  On  the  dorsal  side  of  this  is  the  Neural  Arch,  forming 
with  the  body  the  Neural  Ring,  through  which  the  spinal  cord 
passed. 

3.  From  this  arch  there  extend  projections,  or  Processes. 
Hold  the  vertebra  by  the  tip  of  its  longest  process,  and  place 
it  beside  the  corresponding  vertebra  in  the  complete  skeleton. 
Note  that :  — 

(a)  The  body  is  flattened  where  it  fitted  against  the  verte- 
brae anterior  and  posterior  to  it ; 

346 


Temporal 


Frontal 


Parietal 

-  Occipital 

— •  Cervical  Vertebrae 

Scapula 


Thoracic  Vertebrae 


Lumbar  Vertebrae 


Fibula 


Metatarsus 
Fig.  99.     Side  View  of  the  Human  Skeleton. 


348 


THORACIC    VERTEBRA. 


(b)  The  holes  in  the  vertebrae  form  a  passage  for  the  spinal 
cord; 

(c)  The   middle  process  is  the  Spinous   Process,   and  the 
series  of  spinous  processes  form  the  ridge  of  the  backbone ; 


Body 


Transverse  Process 


Spinous  Process 


Neural  Ring 


Anterior  View  of  Thoracic  Vertebra, 

Demi-Facet  for  Head  of  Rib 


Body 


Anterior  Articular 

Process 


—  Facet  for  Tubercl 
of  Rib 


Transverse  Process 


—  Spinous  Process 


Fig.  100.    Left  Side  View  of  Thoracic  Vertebra. 


(d)  The  two  lateral  processes  are  the  Transverse  Processes. 
Fit  together  two  vertebrae  in  their  proper  order  and  ob- 
serve that :  — 

(e)  The  openings  at  the  sides,  through  which  the  spinal 


CER  VIC  A  L     VER  TEE  RA . 


349 


nerves  passed,  are  formed  by  adjacent  notches,  or  grooves,  in 
the  contiguous  vertebrae. 

(/)  The  two  projections  extending  anteriorly  from  the  ring 
of  one  vertebra  fit  against  two  corresponding  processes  ex- 


Hole  for  Blood  Tubes 


Body  - 


Anterior  Articular  Facet 

..  Neural  Arch 


Spinous  Process 


Neural  Ring 


Anterior  View  of  Cervical  Vertebra 


Body  


Spinous  Process 


Fig.  101.     Left  Side  View  of  Cervical  Vertebra. 


tending  posteriorly  from  the  other  vertebra.     These  are  the 
Anterior  and  Posterior  Articulating  Processes. 

Each  vertebra,  then,  has  seven  processes,  four  articulating 
(two  anterior  and  two  posterior),  two  transverse,  and  one 
spinous. 


350  THE  SPINAL  cozr.u.v. 

The  smooth  places  where  the  articulating  processes  join 
are  called  Facets. 

Observe  on  each  side  of  the  body  of  the  vertebra  a  facet 
where  the  head  of  the  rib  articulated.  There  is  also  a  facet 
on  the  transverse  process  where  the  tubercle  of  the  rib  artic- 
ulated. 

The  first  vertebra,  the  Atlas,  has  no  body.  The  second 
vertebra  is  the  Axis.  It  has  a  peg,  called  the  Odontoid  Process, 
which  represents  the  body  of  the  atlas.  In  shaking  the  head, 
the  atlas,  with  the  head,  turns  on  the  axis.  In  nodding  the 
head,  the  head  simply  rocks  back  and  forth  on  the  atlas.  It 
might,  therefore,  be  claimed  that  it  ought  to  mean  more  to 
say  "no"  than  to  say  "yes/'  because  in  saying  "no"  one 
actually  puts  some  "  backbone "  into  it. 

The  seven  Cervical  vertebrae  (neck)  have  holes  through 
their  sides,  or  transverse  processes,  for  the  passage  of  blood 
tubes. 

The  twelve  rib-supporting  vertebrae  are  the  Thoracic  ver- 
tebras. 

The  next  five  are  the  Lumbar.  The  Sacrum  is  composed  of 
five  vertebrae  grown  together,  and  the  remaining  four  are  com- 
bined in  the  Coccyx. 

Let  the  eye  slowly  review  the  whole  spinal  column,  noting 
what  the  vertebrae  have  in  common.  Note  also  their  differ- 
ences. 

In  most  articulated  skeletons  there  are  pads  of  felt  be- 
tween the  vertebrae.  These  take  the  place  of  the  Inter-ver- 
tebral Cartilages,  which  are  a  form  of  connective  tissue,  possess- 
ing the  elasticity  of  cartilage  and  the  toughness  of  fibrous 
connective  tissue,  such  as  ligament  and  tendon.  These  inter- 
vertebral  cartilages  serve  both  to  keep  the  vertebrae  apart 
and  to  hold  them  together.  When  we  bend  the  shoulders  to 
the  right,  the  right  edges  of  these  cartilages  are  compressed, 


LUMBAR    VERTEBRA. 


351 


and  the  left  edges  are  stretched,  as  a  piece  of  India  rubber 
would  be  if  it  were  glued  between  the  ends  of  two  spools, 
and  the  whole  were  slightly  bent. 


Transverse  Process 


Body 


Neural  Ring 
Anterior  View  of  Lumbar  Vertebra. 


Transverse 
Process 


Body 


Posterior  Articular  Process 
Fig.  102.     Side  View  of  Lumbar  Vertebra.    % 


View  the  spinal  column  from  the  side.  Draw  a  line  repre- 
senting all  its  curves. 

Take  a  thoracic  vertebra,  and,  in  the  presence  of  the  class, 
trim  off  the  processes'  with  a  pair  of  bone-forceps.  The  ver- 


352  MINUTE  STRUCTURE  OF  BONE. 

tebra  will  then  be  seen  to  be,  essentially,  a  ring,  or  padlock, 
consisting  of  the  body  and  neural  ring  or  arch. 

Examine  the  cavity  of  the  skull.  If  the  class  has  not  a 
skull  which  has  been  sawed  across,  look  into  the  skull  cavity 
through  the  hole  where  the  spinal  cord  joined  the  brain. 

Observe  the  conical  shape  of  the  thorax.  In  the  entire 
body  the  bones  and  muscles  about  the  shoulders  usually  make 
a  reversed  cone  of  the  upper  part  of  the  trunk. 

Observe  that  the  ribs  are  connected  with  the  breastbone  by 
cartilages. 

The  upper  limbs  are  articulated  with  the  body  only  where 
the  inner  ends  of  the  collar  bones  join  the  breastbone. 

Rest  the  forearm  on  the  table  with  the  palm  up ;  keeping 
the  elbow  fixed,  turn  the  hand  over.  Turning  the  palm  up  is 
called  Supination ;  turning  it  down  is  Pronation.  Perform 
this  experiment  with  the  articulated  skeleton. 

Examine  the  skeleton  of  a  cat  or  rabbit  for  the  sake  of 
comparison.  Note  especially  the  skull  and  spinal  column,  so 
that  you  will  know  better  what  to  do  when  dissecting  the 
brain  and  spinal  cord  in  one  of  these  animals. 

The  bones  make  about  one-sixth  of  the  weight  of  the 
living  body.  When  dried  they  may  lose  half  of  their 
weight. 

Microscopic  Structure  of  Bone.  —  1.  Hold  a  mounted 
cross  section  of  bone  up  to  the  light,  and  examine  it  with  a 
hand  lens.  The  solid  part  of  the  bone  will  be  seen  to  be 
pierced  by  many  small  holes  (or  if  the  holes  are  filled  they 
will  appear  as.  black  spots).  These  are  the  cross  sections  of 
the  Haversian  Canals,  through  which  run  the  blood  tubes, 
mainly  lengthwise  through  the  bone. 

2.  Examine  the  section  under  the  microscope,  using  a  half- 
inch  objective. 

The   bony  matter   will    now  be   seen  to  be  arranged  in 


MINUTE    STRUCTURE    OF   BONE. 


353 


circles,  Lamellae,  around  the  haversian  canals,  somewhat  like 
the  rings  seen  on  the  end  of  a  log. 

Between   the   rings  are   circles   of   elongated   dark   dots. 
These  are  Lacunas,  cavities  in  which  lay  the  bone  corpuscles 


Lamellc 


Lacunae 


t\      A 


Canalicul 


Fig.  103.    Cross  Section  of  Bone. 
(Highly  Magnified.) 


Haversian  Canal 


which  built  up  the  bone.     The  bone  was,  at  first,  cartilage. 
Later,  mineral  matter  was  deposited  forming  true  bone. 

3.  Now  examine  the  section  under  a  one-fifth-inch  objec- 
tive. From  the  lacunse  there  run  out,  in  every  direction, 
little  crevices,  appearing  as  fine  black  lines.  These  are  the 
Canaliculi.  Through  the  haversian  canals,  lacunse,  and  cana- 


354  COMPOSITION    OF   BONE. 

liculi,  the  nourishing  materials  of  the  blood  reach  all  parts  of 
the  bone. 

The  Chemical  Composition  of  Bone 1.  Take  a  tall, 

narrow  glass  jar,  called  in  the  chemical  laboratory  a  "gradu- 
ate," or  a  lamp  chimney  corked  at  one  end  answers  very  well, 
and  nearly  fill  with  water.  Add  one-sixth  as  much  hydro- 
chloric acid.  Put  into  this  a  slender,  dry  bone,  such  as  a 
fibula  or  rib.  In  twenty-four  hours  take  it  out,  rinse  it 
thoroughly,  and  examine  it.  The  acid  will  probably  have  dis- 
solved out  the  mineral  matter  and  left  the  animal  matter. 

2.  Lay  a  piece  of  bone  on  a  shovel,  or  piece  of  sheet  iron, 
and  place  in  the  fire.  The  animal  matter  is  burned  out, 
leaving  the  brittle  mineral  matter. 

Bone  is  composed  of  mineral  matter,  two-thirds,  and  animal 
matter,  one-third ;  in  childhood  the  animal  matter  is  in  larger 
proportion,  while  in  old  age  the  mineral  matter  is  in  excess. 

The  mineral  matter  is  chiefly  calcium  phosphate,  while 
the  animal  matter  is  largely  gelatin. 

Classification  of  Joints.  —  1.  Immovable,  such  as  the 
sutures  between  the  bones  of  the  skull ; 

2.  Mixed,  such  as  the  joints  between  the  vertebrae; 

3.  Movable,  which  allow  free  motion  between  the  parts ; 

(a)  Ball  and  socket,  as  in  the  hip  and  shoulder ; 

(b)  Hinge,  as  in  the  knee  and  elbow ; 

(c)  Pivot,  as  in  the  forearm,  and  between  the  atlas  and 
axis ; 

(d)  Gliding,  as  between  the  short  bones  of  the  wrist  and 
of  the  ankle. 

Examine  these  joints  in  the  articulated  skeleton,  and  so 
far  as  possible  in  fresh  specimens  (of  rabbits).  Compare 
the  ball  and  socket  joints  of  the  hip  and  shoulder.  Also 
compare  the  hinge  joints  of  the  knee  and  elbow. 

Hygiene  of  the  Bones  and  Joints If  a  bone  is  broken, 


HYGIENE   OF  THE  BONES.  355 

the  person  should  be  moved  as  little  as  possible.  If  neces- 
sary to  move  the  body,  care  should  be  taken  to  keep  the  limb 
straight,  lest  the  sharp  ends  of  the  bones  cut  blood  tubes  and 
other  tissues.  It  is  well  to  tie  some  rigid  object  alongside 
the  broken  limb  to  keep  it  straight. 

Sprains  and  dislocations  are  injuries  to  the  joints,  and 
often  bring  more  serious  results  than  a  broken  bone.  There 
should  usually  be  complete  rest  until  the  part  can  be  used 
without  pain.  Otherwise  a  stiffened  joint  may  result. 


APPENDIX   A. 


THE  following  extended  quotations  are  taken  from  Mrs.  Mary  Hin- 
man  Abel's  Essay  on  Food  and  Cooking  (which  won  the  prize  of  the 
American  Public  Health  Association):  — 

"  Importance  of  Fats.  —  All  the  fats  consumed  by  us,  without  ex- 
ception, are  composed  of  three  bodies  called  neutral  fats,  mixed  together 
in  varying  proportions.  These  three  bodies  are  "olein,"  "palmitin" 
(margarin),  and  "stearin,"  and  the  chief  difference  between  them  is 
that  they  melt  at  different  temperatures ;  the  more  olein  a  fat  has,  the 
more  easily  it  melts,  and  the  less  it  has,  the  more  it  is  like  tallow.  In 
vegetable  oils  we  find,  in  addition  to  these,  small  quantities  of  what  are 
called  'fatty  acids;'  and  in  butter  we  have,  besides  the  three  common 
fats,  a  smaller  per  cent  of  four  scarcer  ones. 

"Practically,  therefore,  all  fats  are  alike;  and  when  absorbed  they 
do  the  same  work  in  the  body,  their  varying  flavors  and  their  colors 
having  nothing  to  do  with  this. 

"  However,  their  flavor,  their  appearance,  and  the  ease  with  which 
they  melt  in  the  mouth  and  in  the  digestive  tract,  have  much  to  do  with 
our  estimation  of  them  as  foods.  Mutton  fat  will  do  our  body  the  same 
service  as  butter;  but  because  of  the  relatively  small  amount  of  olein  it 
contains,  we  have  difficulty  in  swallowing  it. 

"As  to  the  comparative  digestibility  of  these  fats,  it  is  generally  ad- 
mitted that  those  which  melt  at  a  low  temperature,  like  butter  and  vege- 
table oils,  are  most  readily  taken  up  by  the  system;  it  is  thought  that 
we  could  digest  beeswax  if  it  would  melt  in  the  stomach.  Still,  although 
butter  stands  in  common  estimation  as  the  most  digestible,  as  it  is  the 
most  palatable  of  the  fats,  the  stomach  finds  no  trouble  in  disposing  of 
reasonable  amounts  of  any  fats  used  in  the  household. 

"The  fact  that  all  fats  are  so  similar  in  composition,  and  that,  if 
once  digested,  they  will  do  the  same  service  in  the  body,  first  led  scien- 
tists to  try  to  make  out  of  the  cheaper  fats  a  substitute  for  butter.  It 
was  Napoleon  III.  who  set  a  chemist  to  work  to  discover  an  artificial 

357 


358  IMPORTANCE  OF  FATS. 

butter  for  use  in  the  army.  The  chemist  added  butter  color  and  flavors 
made  in  the  laboratory  to  olein  and  margarin  extracted  from  beef 
suet,  and  mixed  with  this  a  little  real  butter;  and  so  successful  was  the 
result  that  the  making  of  artificial  butter  has  become  a  great  industry. 
Now,  certainly  no  one  objects  to  artificial  butter  on  the  ground  that  it  is 
made  of  animal  fats,  for  he  eats  these  every  day  on  his  table ;  he  objects 
because  he  has  doubts  as  to  the  cleanliness  or  the  healthfulness  of  its 
method  of  manufacture. 

"  Therefore,  since  the  substitution,  to  some  extent,  of  animal  fats 
for  butter  is,  from  an  economic  standpoint,  so  desirable,  if  we  cannot 
bring  ourselves  to  use  oleomargarin,  we  must  do  the  best  we  can  in  these 
kitchen  laboratories  of  ours  to  make  other  fats  than  butter  acceptable  to 
the  taste.  .  I ' . 

"People  belonging  to  the  well-to-do  classes,  unless  they  have  given 
special  study  to  the  subject,  seldom  realize  the  importance  of  fat  in  our 
economy.  Fat  means  to  them  fat  meat,  suet,  lard,  and  the  like,  and  the 
much  eating  of  these  is  considered  proof  of  a  gross  appetite;  they  do  not 
consider  how  much  fat  they  take  in  eggs,  in  milk,  in  grains  like  oatmeal 
and  maize;  in  the  seasoning  of  their  varied  dishes,  and  in  their  well-fat- 
tened meats,  where,  as  in  an  average  piece  from  a  very  fat  mutton,  they 
eat  twice  as  much  fat  as  proteid,  without  knowing  it. 

"Indeed,  a  well-fed  man  in  the  upper  classes  may  have  more  fat  in 
his  daily  diet  than  the  freshly  arrived  Mechlenburg  laborer  who  spreads 
a  quarter-inch  layer  of  lard  on  his  bread.  The  latter  cannot  take  his 
fat  in  unsuspected  forms;  he  craves  this  principle  with  his  plain  vege- 
table diet,  and  must  take  it  as  he  can  get  it. 

"  Now  let  us  understand  that  where  economy  is  to  be  considered, 
this  question  of  fat  does  not  take  care  of  itself  as  it  does  for  the  rich 
man.  The  economical  housewife  should  always  keep  in  mind  that  she 
must  furnish  her  family  enough  fat,  and  furnish  it  cheaply.  Butter  is  a 
dear  fat ;  count  out  the  water  in  it  and  see  what  it  costs  you.  We  must 
economize  in  butter  in  as  many  ways  as  possible.  We  must  eat  more  fat 
meat;  first,  that  which  is  ingrained  with  the  lean  where  it  takes  the 
place  of  water,  as  we  have  seen  under  '  Proteids,'  costing  us  practically 
nothing;  when  we  eat  our  vegetables  seasoned  with  such  a  piece  of 
meat,  we  find  them  sufficiently  seasoned.  We  must  also  eat  more  of 
fat  meat  which  we  recognize  as  such,  taking  pains  to  cook  it  so  that  it 
will  be  palatable.  The  crisp,  brown  outside  of  a  roast  is  always  wel- 
come, but  the  fat  of  boiled  beef  or  mutton  will  also  be  relished  if  served 


CARBOHYDRATES.  359 

very  hot.  An  excellent  selection  of  low-priced  beef  is  the  fat  middle 
rib ;  the  lean  part  is  very  tender  and  juicy  when  cooked  in  water  at  a 
low  temperature  for  two  or  three  hours  (or  in  the  heat-saver  mentioned 
below);  and  the  fat,  if  served  very  hot,  any  but  a  pampered  taste  will 
relish.  Too  much  cannot  be  said  in  praise  of  pork  as  furnishing  a  good- 
tasting  and  cheap  fat;  it  can  be  cooked  in  many  ways,  and  used  to  flavor 
vegetables,  etc. 

"It  is  consoling  to  the  economist  to  know  that  little  of  this  food 
principle  will  be  wasted  in  the  body.  Fat  is  more  completely  absorbed, 
according  to  the  testimony  of  the  experimenters,  than  any  other  kind 
of  food,  even  meat. 

"  Carbohydrates,  and  Carbohydrate  -  containing  Foods.  — 
As  we  have  seen,  that  troublesome  body,  cellulose,  plays  here  a  large 
role.  It  is  the  skeleton,  so  to  speak,  of  plants,  built  by  them  out  of  sugar 
and  starch  ;  the  chemist  finds  no  difficulty,  in  his  laboratory,  in  turning 
it  back  into  dextrin  and  sugar,  and  our  stomachs,  too,  can  digest  a  large 
part  of  the  cellulose  of  very  young  and  tender  plants,  from  47  to  62  per 
cent,  it  has  been  found,  of  young  lettuce,  celery,  and  cabbage  ;  but  in 
older  plants,  the  cellulose  proper  becomes  all  intergrown  and  incrusted 
with  substances  of  a  woody  and  mineral  nature,  from  which  even  the 
chemist  separates  it  with  the  greatest  difficulty,  while  our  digestive  juices 
are  entirely  unequal  to  the  task.  Therefore  it  is  that  the  whole  art  of 
the  cook  is  needed  in  treating  this  substance.  She  must  soften  it  ;  she 
must  break  it  up,  and  in  many  cases  separate  it  as  completely  as  pos- 
sible from  the  sugars,  starches,  and  proteids,  which  it  hinders  us  from 
appropriating  to  our  use. 

"  In  some  cases,  as  in  oatmeal  and  in  graham  flour,  we  leave  the 
cellulose,  because  of  its  mechanical  action  on  the  bowels.  To  be  sure, 
this  is  a  wasteful  process,  .for  the  cellulose  carries  with  it,  when  it  leaves 
the  body,  considerable  undigested  food;  but  better  this  way  than  to 
give  the  muscles  of  our  intestines  so  little  work  to  do  that  they  become 
unable  to  digest  any  but  fine,  condensed  food. 

"  As  a  rule,  however,  we  must  think  of  cellulose  not  as  a  food  at  all, 
but  as  a  tough  foreign  body  which  we  must  reckon  with  before  we  can 
utilize  the  proteid  and  fat  particles  of  many  important  vegetable  foods. 

"  The  carbohydrates,  especially  the  starches,  are  the  cheapest  of  the 
food  constituents,  and  therefore  most  apt  to  be  in  excess,  especially  in 
the  food  of  the  poor.  According  to  estimates  already  given,  an  adult 
at  average  hard  work  gets  along  nicely  with  one  and  one-eighth  pounds 


3GO  CARBOHYDRATES. 

of  carbohydrate  material  (meaning,  of  course,  the  dry  amount  of  this 
one  principle),  though  fortunately,  as  mentioned  under  'Fats,'  it  is 
found  that  some  of  this  large  amount  can  be  exchanged  for  fat,  if  the 
body  for  any  reason  can  better  use  the  latter.  Brain-workers  and  the 
richer  classes  the  world  over  take  less  of  carbohydrates,  at  least  in  their 
starch  form,  and  more  proteids  and  fats. 

44  It  has  been  found  that,  as  usually  prepared,  vegetable  foods  give  up 
to  us  from  one-fourth  to  one-half  less  of  their  nutrients  than  do  animal 
foods,  and  especially  is  this  true  of  those  that  are  rich  in  proteids.  To 
illustrate:  a  workman  eats  as  a  part  of  his  dinner  a  dish  of  boiled 
beans ;  but  though  he  rightly  considers  that  he  has  been  eating  a  nour- 
ishing dish,  he  has  really  absorbed  only  60  per  cent  of  the  nitrogenous 
substances  contained  in  it,  the  other  40  per  cent  passing  from  him  un- 
used because  of  its  intimate  connection  with  the  cellulose. 

"  The  starch  part  of  vegetable  food  we  seem  to  get  out  much  better 
than  the  proteid  part,  even  with  our  ordinary  methods  of  cooking; 
thus,  out  of  cooked  rice  we  get  almost  99  per  cent  of  the  starch,  but 
only  80  per  cent  of  what  proteid  it  contains;  flour  in  the  form  of 
noodles  and  macaroni  yields  up  98j  per  cent  of  its  starch  and  80  per 
cent  of  its  albumen;  in  the  form  of  bread  a  little  less  of  each.  The 
potato  will  give  us  only  75  per  cent  of  what  little  proteid  it  contains, 
but  as  high  as  92^  per  cent  of  its  starch. 

"Although  the  starch-containing  foods  are  cheap,  and  although 
they  yield  up  a  good  per  cent  of  this  nutritive  principle,  they  must  not 
be  used  to  excess  for  the  following  reasons :  Starch  must  first  be  turned 
into  sugar  by  our  digestive  juices  before  it  can  be  taken  up  into  the 
blood ;  and  if  the  stomach  is  given  more  at  a  time  than  it  can  master, 
certain  fermentations  may  take  place  and  digestion  be  influenced.  The 
best  authorities  say  that  without  doubt  the  continued  and  severe  diar- 
rheas of  small  children  are  due  to  the  fermentation  of  starch  foods  for 
which  their  digestive  organs  are  not  yet  ready. 

"  These  fermentations,  the  irritating  action  on  the  bowels  of  too 
much  cellulose,  and  the  loss  of  a  good  deal  of  proteid  substance  con- 
nected with  it,  form  the  shady  side  of  a  vegetable  diet.  Even  the  ox 
with  his  many  stomachs  gets  out  of  grass  and  unchopped  hay  only  60 
per  cent  of  the  proteids,  and  50  per  cent  of  the  fats  contained  in  it. 

"  SUGARS.  Most  people  would  class  sugar  among  the  luxuries.  Our 
first  concern,  however,  is  with  its  food  value.  It  gives  us  the  high  fig- 
ure of  99  per  cent  of  the  third  food  principle,  —  carbohydrates.  That 


POTATOES  —  FEUITS.  361 

is,  it  must  be  put  in  the  list  with  bread,  and  it  can  be  used  to  a  certain 
extent  instead  of  bread  and  other  starch  foods.  Moreover,  it  is  espe- 
cially fitted  for  a  food  in  cases  where  nourishment  is  needed  immedi- 
ately, as  it  is  digested  or  absorbed  into  the  system  almost  as  quickly  as 
water,  and  without  taxing  the  digestive  organs,  and  perhaps  on  this  ac- 
count is  its  consumption  so  great  in  our  country.  We  live  fast,  and  we 
want  our  nutriment  in  a  condensed  form. 

"  POTATOES.  We  in  our  country  need  not  feel  as  bitter  against  the 
potato  as  do  the  scientists  of  Europe,  for  we  are  not  obliged  to  use  it 
to  excess ;  and,  considering  its  cheapness  and  availability,  it  is  for  us  a 
good  vegetable,  and  on  these  accounts,  though  it  makes  a  poor  enough 
showing  as  to  food  value,  we  must  rank  it  next  to  the  bean  in  impor- 
tance. It  has  only  2  per  cent  of  proteids,  no  fat,  and  only  20.7  per 
cent  carbohydrates ;  and  yet  since  it  can  be  prepared  in  so  many  ways, 
and  we  never  tire  of  its  mild  flavor,  it  will  doubtless  continue  to  come 
upon  our  tables  more  frequently  than  any  other  vegetable.  But  every 
day,  or  twice  a  day,  in  large  amounts,  is  far  too  often;  indeed,  those 
who  use  it  to  this  extent  must  be  ignorant  of  its  relatively  low  food 
value.  The  quality  of  the  potato  is  of  great  importance,  and  none  but 
the  best  should  be  used.  It  should  be  a  mealy  variety  and  perfectly  ripe. 

"  FRUITS.  Fruits  are  very  useful  to  us  on  account  of  their  flavor 
due  to  various  aromatic  bodies,  fruit  acids,  and  sugar.  The  apple  is 
especially  valuable  on  account  of  its  cheapness  and  fine  keeping  quali- 
ties, and  is  used  in  a  variety  of  ways  by  the  cook  to  give  a  relish  to 
plain  materials.  Although  our  largest  use  of  them  is  in  sweet  dishes, 
they  are  quite  as  valuable  used  without  sugar;  they  may  be  fried  in 
slices  and  eaten  with  fat  meat,  as  bacon  or  sausage. 

"  The  importance  of  dried  fruits  as  food  is  not  well  enough  under- 
stood. Fruit  loses,  in  drying,  a  large  portion  of  its  water,  leaving  its 
nutritive  parts  in  more  condensed  form  for  our  use.  Dried  apples  are 
very  near  to  bread  in  the  per  cent  of  nutriments  they  offer;  and  the 
dried  pear  may  be  called  the  date  of  Germany,  so  general  is  its  use. 
With  us  this  fruit  is  too  expensive,  but  in  parts  of  Germany  the  writer 
has  seen  dried  pears  commonly  exposed  for  sale  by  the  barrel  like  beans. 
They  are  eaten  in  great  quantities  by  the  common  people,  who  seem  to 
digest  them  and  dried  apples  without  any  trouble,  accustomed  as  their 
stomachs  are  to  rye  bread  and  vegetable  diet.  These  dried  fruits  are 
made  into  a  variety  of  dishes  with  meats,  with  potatoes,  and  with 
beans,  and  also  with  noodles  and  macaroni. 


362  SEASONINGS. 

11  Flavors  or  Seasonings.  —  So  far  we  have  had  chiefly  in  mind 
the  real  working  constituents  of  food,  if  we  may  so  speak.  But  many 
things  cannot  be  studied  or  classified  in  the  above  way;  they  must  be 
looked  at  from  another  point  of  view. 

"  Thus,  a  pinch  of  pepper,  a  cup  of  coffee,  a  fine  juicy  strawberry 
—  what  of  these  ?  They  may  contain  all  five  of  the  food  principles, 
but  who  cares  for  the  proteid  action  or  carbohydrate  effects  of  his  cup 
of  good  coffee  at  breakfast,  or  what  interest  for  us  has  the  heating 
effects  of  the  volatile  oil  to  which  the  strawberry  owes  a  part  of  its 
delicious  taste  ? 

"  Surely  the  economical  housekeeper  who  would  throw  out  of  the 
list  of  necessaries  all  of  the  things  that  tickle  the  palate,  that  rouse  the 
sense  of  smell,  that  please  the  eye  and  stimulate  our  tired  nerves,  just 
because  these  things  contain  but  little  food,  would  make  a  mistake. 
She  may  know  just  what  cuts  of  meat  to  buy,  what  vegetables  are 
most  healthful  and  economical,  but  if  she  does  not  understand  how  to 
'  make  the  mouth  water,'  her  labor  is  largely  lost.  Especially  if  she 
has  but  little  money  should  she  pay  great  attention  to  this  subject,  for 
it  is  the  only  way  to  induce  the  body  to  take  up  plain  food  with  relish. 

"  The  list  of  these  spices,  flavors,  harmless  drinks,  and  the  like,  is 
a  long  one.  Unfortunately  we  have  no  comprehensive  word  that  will 
include  everything  of  the  sort,  from  a  sprig  of  parsley  to  a  cup  of 
coffee;  the  Germans  call  them  *  Genuss-mittel '  —  'pleasure-giving 
things.' 

"Without  doubt  'hunger  is  the  best  sauce;'  but  it  is  not  true,  as 
many  think,  that  a  craving  for  variety  is  the  sign  of  a  pampered  and 
unnatural  appetite.  Even  animals,  whom  we  cannot  accuse  of  having 
'  notions,'  have  been  known  to  starve  in  the  experimenter's  hands  rather 
than  eat  a  perfectly  nutritious  food  of  whose  flavor  they  had  wearied, 
and  prisoners  become  so  tired  of  a  too  often  repeated  dish  that  they  are 
made  sick  at  the  sight  and  smell  of  it. 

•'  What  we  call  flavors  may  or  may  not  be  associated  with  a  real 
food.  Meats  are  rich  in  flavors,  and  each  fruit  has  its  peculiar  taste; 
then  there  are  the  spices  and  aromatic  herbs  which  are  not  parts  of  a 
real  food;  and  it  is  most  important  that  the  cook  should  understand  the 
art  of  adding  these  as  seasonings  to  mild-tasting  foods,  so  as  to  make 
new  dishes  which  shall  be  both  nutritious  and  appetizing.  The  bulk  of 
our  nourishment  must  be  made  up  of  the  flesh  of  a  few  animals,  a  half- 
dozen  grains,  and  as  many  garden  vegetables ;  but  the  skillful  cook  can 


SEASONINGS.  363 

make  of  them,  with  the  help  of  other  flavors,  an  endless  variety  of 
dishes. 

"  An  American  traveling  on  the  continent  of  Europe  becomes  ac- 
quainted with  many  new  dishes  and  tastes ;  and  although  not  all  of 
them  are  to  his  liking,  he  must  conclude  that  our  cookery,  compared, 
for  instance,  with  that  of  the  French,  is  very  monotonous.  To  be  sure, 
we  may  have  the  advantage  of  the  European  in  that  our  markets  offer 
us  a  greater  variety  of  natural  foods,  especially  fruits,  each  having  a 
flavor  of  its  own,  and  this  fact  makes  us  somewhat  more  independent 
of  the  art  of  the  cook;  but  still  we  have  need  for  every  lesson  of  this 
sort,  and  especially  is  this  the  case  with  the  poor,  who  must  keep  to  the 
cheapest  of  food  materials,  which  are  not  in  themselves  rich  in  flavor. 

"  Spices  and  other  flavors,  when  not  used  to  excess,  stimulate  our 
digestive  organs  to  appropriate  more  easily  the  food  to  which  they  are 
added;  their  agreeable  odor  starts  the  digestive  juices,  both  in  the 
mouth  and  in  the  stomach ;  and  their  flavors,  acting  on  the  palate,  have 
the  same  effect. 

"  The  more  common  spices  and  flavors,  as  the  housewife  uses  these 
things,  are  salt,  pepper,  mustard,  cinnamon  and  mace,  nutmeg,  cloves, 
ginger,  caraway  and  coriander  seeds,  vanilla,  and  many  volatile  oils, 
such  as  those  contained  in  the  rinds  of  lemons  and  oranges;  and  to 
this  list  we  must  add  certain  vegetables,  as  the  horse-radish  and  various 
members  of  the  onion  family,  the  caper  and  nasturtium  seeds,  and  the 
aromatic  herbs. 

"  All  these  have  their  use  and  their  abuse.  Salt  is  hardly  thought 
of  in  this  list,  so  necessary  do  we  consider  it;  and  its  use  is  well  enough 
governed  by  our  palate,  though  no  doubt  we  over  rather  than  under 
salt  our  food.  Pepper  is  also  in  nearly  every  household  used  to  excess, 
being  added  to  too  many  dishes.  The  pungent  mustard  should  be  still 
more  sparingly  used;  but  a  little  of  it  adds  relish  to  a  salad  or  a  meat 
sauce,  and  goes  especially  well  with  certain  vegetables,  as  beans.  Cin- 
namon, mace,  and  nutmeg,  we  use  principally  with  sweet  dishes,  but 
nutmeg  makes  a  nice  variety  in  certain  meat  stews  and  in  croquettes; 
foreign  cooks  use  it  far  too  much  to  suit  our  taste.  Almost  our  only 
use  of  the  caraway  and  coriander  seeds  is  in  cookies  ;  try  the  former  in 
a  potato  soup  for  variety.  Ginger  seems  to  go  well  with  Indian  meal 
in  pudding  or  porridge,  and  with  molasses  wherever  used. 

"  To  give  the  uses  for  onions  and  for  the  aromatic  herbs  would  be 
too  long  a  task.  The  latter  can  all  be  bought  in  a  dried  state  very 


364  SCOPE  OF  HOUSEHOLD   ECONOM  V. 

cheaply,  and  they  retain  their  flavor  well;  one  of  the  most  useful,  how- 
ever, parsley,  is  much  better  fresh ;  by  all  means  keep  a  little  box  of  it 
growing  in  a  window.  Perhaps,  after  onion,  celery  is  most  useful  for 
soups  and  stews,  root,  stem,  leaves,  and  seeds  being  all  valuable. 

"  In  the  flavoring  of  soups  and  stews,  it  is  well  to  use  a  number  of 
flavors,  letting  no  one  of  them  be  prominent  above  the  others  ;  on  the 
other  hand,  it  is  well  to  have  certain  favorite  dishes  seasoned  always  in 
the  same  way;  as  fresh  pork,  sage;  summer  savory  in  a  bread  dressing, 
and  so  forth. 

"  We  believe  that  it  is  better  to  go  a  little  high  rather  than  too  low 
with  proteid  food.  As  a  rule,  people  who  eat  enough  proteid,  and  es- 
pecially enough  animal  food,  are  vigorous,  and  have  what  we  call 
'stamina;'  and  doctors  incline  to  the  belief  that  such  people  resist 
disease  better  because  their  blood  and  tissues  are  less  watery  than  in 
the  case  of  people  who  draw  their  proteids  almost  entirely  from  such 
vegetables  as  potatoes.  But  many  workingmen  in  America  would  be 
surprised  to  learn  how  well  health  and  strength  can  be  maintained  on 
what  is,  after  all,  not  such  a  very  large  amount  of  meat,  provided  the 
rest  of  the  dietary  contains  enough  vegetable  proteid  and  fat. 

"We  cannot  economize  in  the  amount  of  our  food  beyond  certain 
limits  and  yet  remain  healthy  and  strong;  also,  we  must  not  greatly  alter 
the  relative  proportion  in  which  experience  has  shown  that  these  foods 
are  best  combined.  The  true  field  of  household  economy  has,  then, 
certain  prescribed  limits. 

"  Its  scope  lies  as  follows:  — 

"1.  In  furnishing  a  certain  food  principle  in  its  cheap  rather  than 
in  its  dearer  form;  for  example,  the  proteid  of  beef  instead  of  that  of 
chicken,  fat  of  meat  instead  of  butter. 

"  2.  Having  bought  foods  wisely,  in  cooking  them  in  such  a  manner 
as  to  bring  out  their  full  nutritive  value;  for  instance,  making  a  roast 
juicy  and  delicious  instead  of  dry  and  tasteless. 

"3.  In  learning  how  to  use  every  scrap  of  food  to  advantage,  as  in 
soup-making. 

"If  we  add  to  these  the  art  of  so  flavoring  and  varying  as  to  make 
simple  materials  relish,  we  have  covered  the  whole  field  of  the  house- 
hold economist  so  far  as  the  food  question  is  concerned. 

"  Few  things  are  of  more  importance  than  that  we  should  find  our- 
selves, physically  and  mentally,  equal  to  our  day's  work;  but  not  many 
of  us  realize  how  largely  this  depends  upon  the  food  we  eat. 


SCIENCE  OF  NUTRITION.  365 

"  Supposing  there  to  be  just  enough  money  in  a  given  family  to  buy 
the  right  kind  and  quantity  of  food.  Now,  if  this  money  is  not  wisely 
expended,  or  if  after  the  food  has  been  bought  it  is  spoiled  in  cooking, 
the  results  will  be  very  serious  for  the  members  of  that  family  ;  they 
will  be  undernourished,  and  they  will  suffer  in  clear-headedness,  bodily 
strength,  and,  in  case  of  children,  in  bodily  development. 

"  Surely  the  right  condition  of  the  body  is  too  important  to  be  left 
to  chance  ;  the  best  scientific  knowledge,  the  best  practical  head,  should 
be  at  its  service;  and  this  is  the  case,  indeed,  to  a  large  extent  in  Europe, 
where  the  food  of  the  soldiers  and  of  the  inmates  of  public  institutions 
is  furnished  more  or  less  according  to  certain  rules  that  have  been  de- 
duced, partly  from  observation,  and  partly  from  scientific  experiment. 

"  The  application  of  scientific  principles  on  these  lines  is  not  of 
long  standing,  for  the  investigations  that  have  clinched  them  are  all 
of  comparatively  recent  date.  At  the  end  of  the  last  century  a  begin- 
ning was  made  in  France  and  in  Germany  in  connection  with  the 
philanthropic  effort  to  improve  the  food  of  the  poor,  and  it  was  at  this 
time  Count  Rumford  introduced  into  soup  kitchens  in  Munich  the  soup 
that  has  been  named  after  him.  From  this  time  on,  interest  in  the 
subject  of  food,  both  for  men  and  for  domestic  animals,  steadily  in- 
creased, although  experimenters  were  constantly  coming  to  wrong  con- 
clusions because  the  sciences  of  organic  chemistry  and  physiology,  as 
far  as  they  concerned  the  subject,  were  not  far  enough  advanced. 

"  Every  one  will  admit  that  it  is  of  great  importance  for  the  farmer 
to  know  in  what  proportion  he  shall  lay  in  hay  and  other  food  for 
winter  feeding  of  his  stock  ;  the  animals  must  thrive,  but  there  must 
be  no  waste  by  furnishing  food  in  the  wrong  quantities  or  proportions. 

"  For  the  housewife,  the  food  question,  in  its  relations  to  her 
family,  can  be  stated  in  the  very  same  way.  It  is  important  she  should 
economize,  but  her  path  will  be  full  of  pitfalls  if  she  does  not  under- 
stand in  what  true  economy  consists.  Most  people  with  a  real  interest 
in  the  subject  have  had,  at  some  period  of  their  lives,  certain  pet 
theories  as  to  food.  Perhaps  they  have  been  at  one  time  convinced 
that  most  people  ate  too  much  ;  at  another,  that  meat  was  the  all- 
strengthener  ;  or  they  may  have  been  afflicted  with  the  vegetarian  fad  ; 
and  whatever  their  special  views  may  have  been,  they  have  thought 
that  they  rested  them  upon  facts.  But  surely  they  would  never  have 
pinned  their  faith  to  one-sided  diets  if  they  had  rightly  comprehended 
the  main  facts  of  nutrition.  We  believe  that  if  these  facts  as  at  present 


366  SOUP-MAKING. 

interpreted,  and  the  world's  experience  in  applying  them,  can  be  put  at 
the  command  of  the  housewife,  she  can  use  them  to  great  profit. 

"  Soup-Making.  —  For  one  thing,  we  have  yet  to  learn  the  great 
art  of  soup-making,  and  it  seems  also  of  soup-eating. 

"  The  American  housekeeper  would  say  to  me,  '  This  is  nothing 
new;  for  years  we  have  been  hearing  about  soups.  We  don't  like  soups.' 
I  only  ask,  *  Have  you  tried  them  for  a  considerable  length  of  time,  so 
that  you  have  become  skilled  in  making  them  and  your  family  used 
to  the  taste  ? '  One  fact  alone  ought  to  insure  for  them  a  good  trial,  — 
that  at  least  three  nations,  the  French,  German,  and  Italian,  make 
daily  use  of  them,  and  have  for  generations.  To  take  part  of  our 
food  in  this  form  is  an  absolute  necessity  if  we  are  to  do  the  best 
possible  with  a  certain  amount  of  money. 

"  If  we  do  not  overvalue  either  the  gelatin  or  flavoring  matters  in 
our  meat  soups,  nor  throw  away  the  meat  out  of  which  they  are  made 
we  shall  begin  to  make  soups  on  the  right  basis  ;  that  is,  an  understand- 
ing of  the  real  value  of  the  materials  we  are  working  with,  and  we  shall 
use  meat  for  our  soups  less  often  than  we  now  do  perhaps,  considering 
its  high  price  and  our  great  need  of  it  cooked  in  other  ways.  Soups 
should  not  be  regarded  as  a  luxury,  neither  as  the  last  resort  of  poverty, 
but  as  a  necessary  part  of  a  dinner,  just  as  they  are  now  used  by  all 
classes  in  Europe ;  but  they  need  not  be  made  of  good  cuts  of  meat,  nor 
indeed,  of  meats  at  all. 

"  Lean  meat  of  any  sort,  beef  best ;  fresh,  better  than  that  long 
kept ;  bones  of  next  value,  especially  the  spongy  rib  bones  and  ver- 
tebrae. Saw  and  chop  the  bones  into  little  pieces  ;  cut  the  meat  small. 
Soft  water  is  better  than  hard. 

"  Keep  a  kettle,  if  possible,  for  this  purpose  alone,  and  add  to  it  all 
bits  of  meat  and  bones  as  they  accumulate.  Put  the  meat  into  cold 
water,  let  it  stand  some  hours  if  possible,  heat  very  gradually,  and  keep 
simmering.  Two  hours  or  less  brings  out  all  the  flavors  of  the  meat, 
but  a  much  longer  time  is  necessary  to  get  all  the  nutriment  from  the 
bones. 

"  Do  not  remove  the  scum  ;  it  contains  the  albumen  of  the  soup, 
and  nothing  objectionable  if  the  meat  was  well  cleaned. 

"  An  hour  before  the  soup  is  served  add  flavors  ;  onions  and  carrots 
are  the  best,  celery,  summer  savory,  and  parsley  next.  Use  others,  as 
cloves,  nutmegs,  bay  leaf,  etc.,  only  occasionally.  Add  salt  and  pepper 
just  before  serving. 


THE  HEAT-SAVER.  367 

"  When  done,  strain  and  skim  off  all  fat  (better  if  left  to  stand  till 
next  day,  the  fat  removed,  and  the  soup  simply  re  warmed),  and  make 
such  additions  as  you  wish. 

41  The  Heat  Saver.  —  It  is  a  part  of  common  information  that  the 
inhabitants  of  northern  countries  make  extensive  use  of  non-conducting 
substances,  like  wool,  for  preventing  the  escape  of  heat  from  a  vessel  in 
which  cooking  is  going  on.  It  is  strange  that  we  do  not  make  more  use 
of  such  appliances,  for  they  have  often  been  described  and  illustrated  ; 
it  is  probably  because  they  are  not  found  ready  made,  and  with  a  com- 
plete list  of  directions  for  use.  The  writer  made  and  used  a  cooker  of 
this  sort,  and  after  considerable  modification  and  experiment  it  became 
a  very  useful  thing  in  the  kitchen.  If  you  wish  to  cook  meat  at  the 
proper  temperature,  this  contrivance  makes  it  possible  to  do  so,  and  is 
also  very  saving  of  fuel. 

"  Take  a  packing-box  measuring,  say,  two  feet  each  way,  and  cover 
the  bottom  with  a  layer  of  packed  wool  four  to  six  inches  thick  ;  set  into 
the  middle  of  this  another  box  or  cylinder  of  sheet  iron,  and  fill  the 
space  between  the  two  with  a  layer  of  wool  four  to  six  inches  thick, 
and  closely  packed.  Into  the  inner  compartment  put  your  kettle  of 
meat  or  vegetables  already  brought  to  the  boiling-point  and  having  a 
tightly  fitting  cover,  and  over  this  press  a  thick  pillow  or  woolen  blanket. 
Then  fasten  down,  tight  over  all,  the  lid  of  your  box.  As  the  heat  in 
the  water  must  finish  the  cooking  already  begun,  this  amount  must  be 
rightly  proportioned  to  the  amount  of  food  to  be  cooked  ;  for  example, 
two  quarts  of  water  to  one  and  one-half  pounds  of  beef  rib  were  used. 
The  water  was  brought  to  the  boiling-point,  the  meat  placed  in  it,  and 
allowed  to  boil  for  five  minutes,  the  pot  was  then  tightly  covered,  placed 
in  the  box  and  allowed  to  remain  three  hours.  At  the  end  of  that  time 
the  meat  was  tender. 

"  Introduction  to  Bills  of  Pare.  —  (To  the  Mother  of  the  Fam- 
ily.) In  the  general  introduction  the  writer  has  stated  a  few  princi- 
ples that  should  guide  us  in  choosing  our  food.  We  have  learned  that 
to  keep  us  in  good  health  and  working  order  we  ought  to  have  a  certain 
amount  of  what  is  best  furnished  by  meat,  eggs,  milk,  and  other  animal 
product,  and  that  we  must  also  have  fat  as  well  as  what  is  given  us  in 
grains  and  vegetables. 

"  But  now  our  work  has  only  just  begun  ;  for  we  are  to  furnish  these 
food  principles  in  the  shape  of  cooked  dishes  to  be  put  on  the  family 
table  three  times  a  day;  and  the  dishes  must  not  only  be  nourishing,  but 


368  BILLS  OF  FARE. 

they  must  taste  good,  and  there  must  be  plenty  of  variety  from  day  to 
day;  and  last, — and  this  is  the  hardest  point  of  all,  —  we  are  to  do 
this  for  the  sum  of  thirteen  cents  per  person  daily. 

"  I  am  going  to  consider  myself  as  talking  to- the  mother  of  a  family 
who  has  six  mouths  to  feed,  and  no  more  money  than  this  to  do  it  with. 
Perhaps  this  woman  has  never  kept  accurate  account,  and  does  not  know 
whether  she  spends  more  or  less  than  this  sum.  She  very  likely  has  her 

*  flush '  days  and  her  *  poor '  days,  according  to  the  varying  amount  of 
the  family  earnings;  and  it  may  be  a  comfort  to  her  to  know  that  if 
she  could  average  these  days  and  plan  a  little  better  she  can  feed  her 
family  nicely  on  this  sum. 

"  A  few  facts  as  to  what  the  writer  knows  to  have  been  done  in  this 
line  will  not  be  amiss.  I  knew  a  family  of  six  belonging  to  one  of  the 
professional  classes,  half  grown  people  and  half  children,  that  lived  for 
a  year  on  an  average  of  eleven  cents  per  person  daily,  and  no  one  would 
have  said  that  they  did  not  live  well  enough  ;  and  they  had  meat  about 
four  days  out  of  the  seven  ;  there  was  always  cake  on  the  supper  table, 
and  they  used  plenty  of  fruit. 

"Here  is  an  average  bill  of  fare:  Breakfast  —  milk  toast,  fried 
potatoes,  coffee  ;  dinner  —  soup  made  of  shank  of  beef,  fried  liver,  rice 
writh  potatoes  ;  supper  —  bread  and  butter,  fried  mush,  stewed  pears, 
and  cake.  Next  day  there  was  pressed  beef  made  from  the  soup  meat 
chopped  and  flavored,  and  next  there  was  cheap  fish  nicely  fried.  The 
head  of  this  household  was  a  skillful  economist,  absolutely  no  mistakes 
were  made  in  cooking,  and  not  a  scrap  was  wasted.  She  had  a  long 
list  of  simple  dishes  at  her  command,  and  she  specially  studied  variety. 

*  I  abandon  even  a  favorite  dish  for  weeks,'  she  said,  '  if  any  one  tires 
of  it.'     I  give  this  as  a  sample  of  what  I  know  to  have  been  done  by 
a  highly  respectable  family  in  a  city  of  small  size  in  one  of  our  Eastern 
States. 

"  It  must  be  mentioned  that  the  price  on  which  this  family  lived  in 
comfort  could  not  have  been  so  low  as  it  was  but  for  one  great  help,  — 
they  had  a  garden  that  furnished  green  vegetables  and  a  little  fruit. 
But  then  most  every  family  has  some  special  advantage  that  would 
lower  the  rate  somewhat  ;  one  buys  butter  or  fruit  advantageously  of 
friends  in  the  country,  another  can  buy  at  wholesale  when  staples  are 
cheaper,  still  another  may  be  able  to  keep  a  few  fowls,  and  so  on. 
Numerous  instances  could  be  brought  to  prove  that  the  food  for  a  family 
can  be  purchased  in  a  raw  condition  for  the  sum  per  head  for  which 


THE  FOOD  PROBLEM.  369 

we  have  undertaken  to  buy  it,  and  that  skill  in  cooking  and  flavoring, 
and  by  giving  right  variety,  a  healthful  and  acceptable  diet  can  be 
furnished,  though  it  cannot,  of  course,  contain  luxuries. 

u  Another  thing,  when  I  speak  of  a  woman  who  is  to  buy  the  food 
of  a  family  for  thirteen  cents  apiece  daily,  I  have  in  mind  the  wife  of 
a  man  who  earns  this  sum  himself,  the  wife  having  her  time  to  attend 
to  her  housework  and  children.  If  a  woman  helps  to  earn,  as  in  a 
factory,  doing  most  of  her  housework  after  she  comes  home  at  night, 
she  must  certainly  have  more  money  than  in  the  first  case  in  order  to 
accomplish  the  same  results,  for  she  must  buy  bread  already  baked,  and 
can  only  cook  those  dishes  that  take  the  least  time. 

"  I  shall  take  for  granted  that  you  have  the  kitchen  utensils  described 
on  page  twenty  ;  if  not,  buy  them,  because  you  cannot  afford  to  be  with- 
out them.  Food  is  very  expensive  compared  with  pots  and  pans  ;  you 
must  not  spoil  food  for  lack  of  the  right  things  to  cook  in. 

"I  only  ask  you  in  advance  to  try  the  recipes  I  shall  give  you,  and 
to  try  and  lay  aside  your  prejudices  against  dishes  to  which  you  are  not 
accustomed,  as  soups  and  cheese  dishes,  for  instance.  You  cannot 
afford  to  reject  anything  that  will  vary  your  diet,  for  many  good-tasting 
things  you  cannot  buy.  I  know  it  is  hard  for  a  busy  woman  to  give 
her  cooking  a  bit  more  time  than  will  '  just  do,'  but  if  you  make  it  a 
rule  to  determine  the  night  beforehand  just  what  you  will  cook  the  fol- 
lowing day,  no  matter  how  simple  the  food  may  be  you  will  gain  this 
result ;  with  the  materials  at  your  disposal  you  will  put  before  your 
family  much  better  food,  and  they  will  call  you  a  good  cook,  and  think 
that  no  family  need  live  better  than  they  ;  and  this  impression  will  be 
made  from  your  having  the  right  variety.  Let  us  understand,  to  begin 
with,  that  it  is  your  business  in  life  just  now  to  conquer  the  food  ques- 
tion as  it  affects  your  family.  Just  as  the  business  man  must  watch  the 
market  and  take  advantage  of  a  half  cent  a  pound  on  an  article  that 
he  may  successfully  compete  with  his  neighbor,  so  you  must  be  on  the 
alert  to  use  every  possible  advantage.  It  is  a  struggle  in  which  energy 
and  calculation  will  tell  for  a  great  deal,  and  you  will  have  solid  enjoy- 
ment in  every  point  you  gain. 

"In  buying  meat,  your  saving  cannot  be  so  much  in  quantity  as 
quality.  Try  to  learn  the  different  parts  of  the  animal,  and  to  dis- 
tinguish between  meat  from  a  fat  ox  and  a  lean  one;  for,  as  we  have 
explained,  the  former  has  less  water  in  it,  and  why  should  you  pay 
good  money  for  that  which  nature  gives  you  free  ?  In  winter  try  to 


370  THE  FOOD  PROBLEM. 

buy  meat  ahead  so  that  you  can  make  it  tender  by  keeping  it;  and  you 
will  notice,  too,  that  the  larger  the  piece  you  buy,  the  smaller  the  per 
cent  of  bone  you  get  with  it. 

"  The  per  cent  of  bone  in  the  whole  animal,  as  in  the  case  of  an  ox, 
is  not  more  than  ten  to  eleven  per  cent;  but  the  buyer  of  a  small  piece 
often  gets  twice  that  proportion.  As  we  have  said  again  and  again  in 
tbese  pages,  the  low-priced  or  tougher  parts  have  as  much  nutriment 
for  you  as  the  rib  roast  which  is  beyond  your  purse.  Choose  often  the 
fat  middle  rib,  and  cook  it  long  and  slowly  ;  buy  the  neck  and  scrag  of 
mutton,  and  make  a  stew  with  vegetables  ;  buy  half  a  calf's  head,  and 
see  what  a  fine  soup  you  can  make  of  it.  Have  beef's  liver  now  and 
then  and  tripe,  rather  than  put  your  money  into  sausage  of  doubtful 
quality.  By  all  means  buy  fish  when  it  is  cheap,  catfish  for  instance, 
which  are  excellent  fried.  Keep  suet  always  on  hand,  and  use  it  instead 
of  butter,  as  has  been  directed. 

"  No  one  need  tell  you  how  valuable  salt  pork  and  bacon  are  for 
you;  the  only  danger  is  that  you  will  use  too  much  of  them. 

"  In  buying  eggs,  you  must  be  governed  by  the  price ;  in  winter  use 
as  few  as  possible,  and  even  in  the  spring,  when  they  are  cheaper,  re- 
member that  they  are  not  as  cheap  as  the  lowest  priced  cuts  of  meat 
from  fat  animals.  But  when  they  cost  only  fifteen  cents  a  dozen  you 
can  well  disregard  any  small  comparison  of  nutritive  values  in  con- 
sideration of  their  high  worth  in  furnishing  variety  ;  you  can  afford  to 
use  them  now  and  then  in  place  of  meat,  and  in  making  various  egg 
dishes. 

"  Of  the  value  of  cheese  to  take  the  place  of  meat,  you  can  read  in 
another  part  of  this  essay.  Buy  it  once  a  week  at  least,  the  skim 
variety  if  you  cannot  afford  the  other,  and  grate  and  cook  it  according 
to  the  recipes  given. 

"  Try  to  find  a  reliable  milkman,  and  buy  skim  milk  at  half  the  price 
of  full,  and  use  it  for  all  cooking  purposes,  keeping  full  milk,  and  if 
possible  a  little  of  the  cream,  for  coffee. 

"  Now  let  us  take  the  vegetable  part  of  your  diet.  You  must  keep 
on  hand  every  kind  of  flour  and  grain  that  is  not  too  expensive  ;  be 
thankful  that  wheat  flour  is  so  good  and  cheap,  it  will  be  your  best 
friend.  If  you  are  not  already  skillful  in  the  use  of  doughs,  you  will 
waste  your  materials  and  make  mistakes  at  first;  but  there  is  nothing 
for  you  but  to  become  mistress  of  this  department  of  cookery.  Use 
bread  freely  in  all  bread  dishes;  learn  how  to  make  every  one.  You 


FLAVORINGS.  371 

will  use  buckwheat  for  cakes,  rice  for  puddings,  barley  in  soups,  oat- 
meal and  cornmeal  for  mushes  ;  you  must  learn  to  use  them  all  in  as 
many  ways  as  possible.  The  grains  are  cheaper  foods  for  us  than  vege- 
tables, although  dried  peas,  beans,  and  lentils  follow  hard  upon  them. 
Even  the  potato,  which  may  be  called  our  favorite  vegetable,  is  more 
expensive  than  wheat  flour,  if  we  are  talking  only  of  food  values. 

"Except  in  the  height  of  their  season  have  nothing  to  do  with 
green  vegetables,  at  least  not  under  the  impression  that  they  are  cheap; 
if  you  buy  them,  know  that  you  are  paying  for  flavors  and  variety 
rather  than  for  food.  But  even  in  the  early  spring  buy  plenty  of  such 
vegetables  as  onions,  carrots,  parsley,  and  other  green  herbs  for  your 
soups  and  stews.  When  you  go  for  a  walk  in  the  country,  be  sure 
to  bring  home  some  mint  and  sorrel  in  your  pocket;  the  former  will 
make  a  nice  meat  sauce,  the  latter  a  delightful  flavor  in  soup.  It  will 
be  perfectly  easy  for  you  to  grow  in  the  window-box  that  delicious  herb 
parsley,  and  have  it  always  fresh. 

"  For  a  low  purse  there  is  no  help  so  great  as  a  knowledge  of  flavor- 
Ings.  When  we  remember  that  we  can  live  on  bread,  beans,  and  peas, 
and  a  little  cheap  meat  and  fat  the  year  round,  if  we  can  make  it  '  go 
down,'  we  shall  realize  the  importance  of  such  additions  as  rouse  the 
appetite  ;  there  is  room  here  for  all  your  skill  and  all  your  invention. 
Always  make  a  cheap  but  nutritious  dish  inviting  in  appearance  ;  espe- 
cially does  this  influence  the  appetites  of  children,  who  are  delighted 
with  a  very  plain  cake  if  only  a  few  raisins  or  some  sugar  appear  on  the 
top. 

"  The  bills  of  fare  (given  below)  where  seventy-eight  cents  covers 
the  cost  of  food  for  a  family  of  six  per  day,  and  where  the  amount  of 
food  is  carefully  weighed  and  estimated,  is  meant  to  suggest  to  you  how 
in  a  few  cases  your  food  problem  can  be  solved.  You  can,  no  doubt, 
spend  the  money  in  ways  that  will  better  suit  the  tastes  of  your  family; 
but  I  beg  you  to  examine  anew  your  favorite  dishes  to  see  if  they  are  as 
nutritious  as  they  should  be  for  their  price.  Remember  that  the  pro- 
teid  column  is  the  one  you  must  look  to  most  carefully,  because  it  should 
not  fall  below  the  figures  I  give.  If,  for  instance,  you  should  economize 
on  meat  in  order  to  buy  cake  and  pastry,  this  column  would  suffer  at  the 
expense  of  the  Other  two,  and  the  family  would  be  undernourished."  — 
ABET,. 

The  Aladdin  Oven.  —  Of  all  the  appliances  for  cooking  that  are 
known  to  the  writer,  the  most  valuable  is  the  "Aladdin  Oven,"  in- 


372  THE  ALADDIN  OVEN. 

vented  by  Edward  Atkinson.  It  consists  of  a  sheet-iron  oven,  with 
snugly  fitting  door.  This  is  placed  within  an  outer  casting  made  of 
non-heat-conducting  material.  There  is  a  space  between  the  inner 
oven  and  the  outer  box,  and  between  the  two  heat  is  held  and  applied 
to  the  work  of  cooking.  Since  little  heat  is  lost,  not  a  great  amount  is 
required,  and  a  common  kerosene  lamp  supplies  all  the  heat  that  is 
needed.  The  lamp  is  placed  beneath  the  oven  under  a  hole  in  the 
outer  box.  This  hole  is  four  inches  across,  but  is  usually  reduced  to 
two  and  a  half  inches  by  a  lid  fitting  over  it.  It  will  probably  be  a 
matter  of  surprise  to  those  who  hear  it  for  the  first  time,  that  bread 
can  be  baked  in  such  an  apparatus,  but  the  writer's  experience  is  that 
of  others  who  have  tried  ;  namely,  not  only  that  it  is  repeatedly  done, 
but  that  the  bread  thus  cooked  is  superior  to  bread  baked  in  an  ordi- 
nary oven.  The  cooking  in  the  "Aladdin  Oven"  is  slow  cooking. 
Many  of  the  scientific  cooks  repeatedly  tell  us  that  we  must  not  employ 
too  high  a  heat  in  cooking.  And  this  slow  cooking  at  a  lower  tempera- 
ture gives  better  result  in  nearly  every  kind  of  cooking.  Mattieu 
Williams,  in  his  Chemistry  of  Cookery,  tells  us  that  "to  boil  meat  is 
to  spoil  it."  And  the  description  of  the  "  Heat  Saver,"  given  on  page 
367  illustrates  the  gain  in  saving  of  fuel,  and  in  the  better  condition  of 
the  food  after  it  is  cooked.  Mrs.  Ellen  H.  Richards,  one  of  the  best 
authorities  on  this  subject,  in  speaking  of  the  requirements  of  an  ideal 
cooking  apparatus,  says  :  — 

"  1.  The  degree  of  heat  should  be  under  perfect  control ;  increased, 
diminished,  or  withdrawn  at  will,  and  without'  loss  of  time.  Solid 
fuel  demands  constant  and  equable  running,  and  gives  the  best  results 
when  used  in  large  masses.  The  small  fire-box  of  a  cook-stove,  and  the 
urging  of  the  fire  for  a  short  time  three  times  a  day,  are  fatal  objections 
to  the  use  of  anthracite. 

"2.  A  tightly  closed  vessel  heated  by  steam,  or  hot  water,  or  hot 
air,  offers  many  advantages  over  the  top  of  a  red-hot  stove  or  the 
inside  of  a  nearly  red-hot  cast-iron  oven  for  cooking,  except  for  the 
broiling  and  the  roasting  of  meat,  and  for  some  other  methods  of 
cookery  which  require  the  quick  application  of  heat. 

"  3.  For  all  purposes  of  slow  cooking,  the  oven  should  have  a  non- 
conducting covering  which  retains  the  heat  where  it  is  wanted,  and 
also  allows  of  tight  closing,  and  of  security  from  the  constant  watching 
required  by  the  fitful  heat  of  a  stove.  This  use  of  a  close  oven  with  a 
non-evaporative  atmosphere  seems  to  be  the  secret  of  the  retention 


THE  ALADDIN  OVEN.  373 

of  the  delicate  and  volatile  flavors  which  usually  flavor  the  house  and 
street,  and  not  the  food  as  it  is  brought  to  the  table." 

After  thus  outlining  the  ideal  cooker,  she  goes  on  to  say,  "  For  sim- 
plicity, effective  use  of  heat,  economy  of  fuel,  and  development  of  fla- 
vor in  the  food  cooked,  combined  with  increase  of  its  digestibility,  the 
*  Aladdin  Oven  '  is  an  apparatus  far  exceeding  in  merit  any  other  now 
on  the  market." 

Among  the  many  advantages  of  the  "  Aladdin  Oven  "  the  following 
may  be  named  :  — 

1.  The  greater  digestibility  of  the  food  cooked  in  it.     In  the  high 
heat  of  the  ordinary  oven  many  foods  are  so  altered  by  the  great  heat  as 
to  become  very  indigestible.     This  is  notably  so  in  the  case  of  fat.     The 
high  heat  in  some  way  breaks  up  the  fat  so  as  to  make  it  exceedingly 
indigestible  and  injurious  to  most  stomachs.     The  more  moderate  heat 
of  the  "Aladdin  Oven  "  cooks  fat  pork  and  bacon  so  that  even  delicate 
stomachs  find  it  palatable  and  digestible.     In  the  use  of  this  cooker  in 
his  own  family  the  writer  knows  that  many  dishes,  cooked  by  this  slow 
process,  are  readily  taken  and  assimilated,  which,  when  cooked  in  the 
common  stove,  were  difficult  of  digestion. 

2.  Another  feature  is  its  economy.     (1).  In  economy  of  food,  little 
is  spoiled,  as  it  is  difficult  to  overcook  or  burn  anything.     (2)  Economy 
of  fuel.    A  quart  or  so  of  kerosene  will  do  the  cooking  for  a  family  for  a 
day.     (3)  Economy  of  time  and  labor.     In  much  of  the  cooking  on  the 
ordinary  stove  the  food  must  be  constantly  watched,  often  stirred,  while 
the  cook  is  subjected  to  a  very  uncomfortable  heat.     Most  dishes  can  be 
Put  into  the  "  Aladdin  Oven,"  and  left  entirely  alone  until  they  are  com- 
pletely cooked.     Of  course  it  takes  some  experience  to  know  just  what 
degree  of  heat  to  apply,  and  how  long  it  takes  for  a  given  food  or  a  given 
weight  to  be  cooked.     For  instance,  much  of  the  cooking  can  be  done 
at  night.     The  materials  for  breakfast  being  put  into  the  oven  in  the 
evening,  will  be  all  ready  for  breakfast,  and  hot  for  either  a  late  or  an 
early  breakfast.     The  comfort,  especially  in  the  summer,  and  conven- 
ience to  the  cook,  can  hardly  be  overestimated. 

3.  Using  a  liquid  fuel  makes  it  as  easy  to  regulate  as  a  common 
lamp  ;  there  are  no  ashes,  no  dust,  no  more  odor  than  from  a  lamp,  and 
that  is  hardly  noticeable  if  the  lamp  is  kept  clean.     Any  contrivance 
that  will  enable  one  to  set  the  breakfast  to  cooking  before  he  goes  to 
bed,  with  no  more  trouble,  so  far  as  the  fire  is  concerned,  than  to  light 
a  common  lamp  and  place  it  under  the  oven ;  and  in  the  morning  to 


374  THE  ALADDIN  OVEN. 

have  little  more  to  do  than  to  transfer  the  dishes  from  the  oven  to  the 
table  (for  many  foods  can  be  cooked  in  the  same  dishes  in  which  they 
are  served)  ;  certainly  every  family  where  time  and  labor  are  worth 
economizing  should  hail  this  apparatus  with  delight.  It  is  the  wonder- 
ful lamp  of  "  Aladdin  "  that  brings  Health,  Comfort,  and  Economy. 

The  inventor  seeks  no  gain  for  this  ingenious  cooker.  He  has  do- 
nated his  patent  to  the  world.  He  has  also  supplemented  the  oven  by 
a  very  valuable  treatise  on  The  Science  of  Nutrition  and  the  Art  of 
Cooking.  (Published  by  Damrell  &  Upham,  Boston,  Mass.) 

READING.  —  Practical  Sanitary  and  Economic  Cooking,  Abel  ;  The 
Science  of  Nutrition  and  the  Art  of  Cooking,  Atkinson ;  Chemistry 
of  Cookery,  Williams  ;  Chemistry  of  Foods  and  Nutrition,  Atwater 
(Century  Magazine,  1887-88)  ;  Eating  for  Strength,  Holbrook; 
Foods,  Smith  ;  Disorders  of  Digestion,  Brunton  ;  Indigestion  and 
Biliousness,  Fothergill  ;  Philosophy  of  Eating,  Bellows  ;  Handbook 
of  Invalid  Cooking,  Boland. 


BILL    OF  FARE. 


375 


SAMPLE  OF  BILL  OF  FARE  AND   MATERIALS   FOR   FAMILY  OF  SIX, 
AVERAGE  PRICE  78  CENTS  PER  DAY,  OR  13  CENTS  PER  PERSON. 

—  (ABEL.) 


MONDAY,  MAY. 

BKEAKFA  S  T.                                      DINNER. 
OATMEAL,  MUSH,  WITH         «            PEA  SOUP  (p.  117).* 
MILK  AND  SUGAR.                       MUTTON  STEW  (p.  52). 
BREAD.                                    BOILED  POTATOES. 
COFFEE.                                             BREAD. 

SUPPER. 

BREAD  PANCAKES 

(p.  93) 

FRIED  BACON. 

TEA. 

PRO- 

FATS 

CARBO- 

COST 

TEIDS 

HYDRATES 

IN 

• 

oz. 

oz. 

oz. 

CENTS 

2  Eggs  . 

.34 

.32 

3 

%  Ib.  Oatmeal    .... 

1.74 

.72 

7.80 

3| 

%  Ib.  Coffee  

3| 

7.92 

8| 

1)£  qts.  Skim  Milk      .     . 

1.59 

.36 

1.48 

"2 

6 

.36 

9.60 

9 

4  Ibs.  Potatoes   .... 

1.28 

13.24 

5 

4  Ibs   Bread 

3.84 

.32 

33.20 

91 

1  qt.  Whole  Milk    .     .     . 

1.16 

1.24 

1.66 

o 

7 

3  Ibs.  Shoulder  of  Mutton, 

8.16 

2.88 

.  . 

21 

1  Ib.  Peas,  Dried     .     .     . 

3.68 

.32 

8.32 

5 

Vz  Ib   Flour 

.96 

.12 

5.72 

U 

Total     

A  j 

23.11    • 

15.88 

80.34 

77.3 

Required  

19.19 

12.42 

78.03 

78 

*  Page  numbers  refer  to  Mrs.  Abel's  Practical  Sanitary  and  Economic  Cooking, 


376 


BILL    OF  FARE. 


SAMPLE  OF  BILL  OF  FARE  AND  MATERIALS  FOR  FAMILY  OF  SIX, 
AVERAGE  PRICE  $1.38  PER  DAY,  OR  1W  CKXTS  PER  PERSON.— (ABEL.) 


MONDAY,  JANUARY. 

BREAKFAST.                                                   DINNER. 

BUCKWHEAT  CAKES.                       PEA  SOUP  (p.  118). 
SAUSAGE.                                       ROAST  BEEF. 
COFFEE.                                    BAKED  POTATOES. 
APPLE  SAUCE.                            CANNED  TOMATOES. 
BARLEY  GRUEL  (p.  121). 

SUPPER. 

POTATO  SOUP  WITH  EGG  AND  BREAD 

BALLS  (p. 

128). 

BROWN  BREAD  AND  BUTTER. 

CANNED 

FRUIT. 

TEA. 

PRO- 

TKIDS. 

FATS. 

CARBO- 
HYDRATES. 

COST 

IX 

OZ. 

oz. 

oz. 

CENTS. 

2  Ibs.  Buckwheat  Flour  . 

3.04 

64 

23.20 

10 

1  Ib.  Sausage     .... 

2.32 

6.00 

.  . 

12 

2  Ibs   Beef 

6.72 

1.76 

32 

3  Ibs.  Potatoes  .... 

.96 

9.94 

3| 

2  Ibs.  Tomatoes  (canned 

at  home)    .... 

.19 

.  . 

3.50 

6 

3  Ibs.  Bread       .... 

.2.88 

.24 

24.90 

«ft 

2  Eggs      

.34 

.32 

.  . 

<l 

%  Ib.  Barley     .... 

.88 

.12 

5.72 

4 

1  qt.  Whole  Milk  ..." 

1.16 

1.23 

1.65 

7 

%  Ib.  Sugar      .... 

.  . 

.  . 

7.92 

^ 

1  Ib.  Dried  Peas    .     .     . 

3.68 

.32 

8.32 

5 

)£  Ib.  Butter     .... 

.  . 

6.66 

.  . 

M| 

Canned  Fruit    .... 

.  . 

.  . 

.  . 

10 

%  Ib.  Coffee      .... 

.  . 

.  . 

.  . 

31 

Tea      

2 

Apples     

5 

Total     

17.29 

*  ° 

22.17 

85.15 

1271 

Required 

19.19 

12.42 

78.03 

5 

138 

APPENDIX   B. 


Antiseptics  and  Disinfectants.  —  The  following  is  chiefly  from 
Sternberg's  Manual  of  Bacteriology,  and  embodies  part  of  the  report 
of  "  The  Committee  on  Disinfectants  of  the  American  Public  Health 
Association." 

An  Antiseptic  is  a  substance  having  the  power  to  prevent  or  destroy 
putrefaction,  or,  what  is  the  same  thing,  the  bacteria  upon  which  putre- 
faction depends. 

Disinfection  is  the  destroying  of  disease  germs  by  means  of  heat, 
chemic  substances,  fumigation,  or  by  fresh  air  or  sunlight. 

"  The  injurious  consequences  which  are  likely  to  result  from  such 
misapprehension  and  misuse  of  the  word  '  disinfectant '  will  be  appre- 
ciated when  it  is  known  that  recent  researches  have  demonstrated  that 
many  of  the  agents  which  have  been  found  useful  as  deodorizers  or  as 
antiseptics  are  entirely  without  value  for  the  destruction  of  disease 
germs. 

"  This  is  true,  for  example,  as  regards  the  sulphate  of  iron,  or  cop- 
peras, a  salt  which  has  been  extensively  used  with  the  idea  that  it  is  a 
valuable  disinfectant.  As  a  matter  of  fact,  sulphate  of  iron  in  saturated 
solution  does  not  destroy  the  vitality  of  disease  germs,  or  the  infecting 
power  of  material  containing  them.  This  salt  is,  nevertheless,  a  very 
valuable  antiseptic,  and  its  low  price  makes  it  one  of  the  most  valuable 
agents  for  the  arrest  of  putrefactive  decomposition." 

EXTRACTS  FROM  THE  ABOVE-MENTIONED  REPORT. 
"The  most   useful  agents  for  the  destruction   of   spore-containing 
infectious  material  are:  — 

1.  Fire  ;  complete  destruction  by  burning. 

2.  Steam  under  pressure,  105  degrees  C.  (221  degrees  F.).  for  ten 
minutes. 

3.  Boiling  in  water  for  half  an  hour. 

4.  Chlorid  of  lime  ;  a  four  per  cent  solution. 

377 


378  DISINFECTANTS. 

5.    Mercuric  chlorid  ;  a  solution  of  1.500. 

For  the  destruction  of  material  which  owes  its  infecting  power  to 
the  presence  of  inicro-organisms  not  containing  spores,  the  committee 
recommends  :  — 

1.  Fire  ;  complete  destruction  by  burning. 

2.  Boiling  in  water  for  ten  minutes. 

3.  Dry  heat  ;  110  degrees  C.  (230  degrees  F.)  for  two  hours. 

4.  Chlorid  of  lime  ;  a  two  per  cent  solution. 

5.  Solution  of  chlorinated  soda  ;  a  ten  per  cent  solution. 

6.  Mercuric  chlorid  ;  a  solution  of  1  :  2,000. 

7.  Carbolic  acid  ;  a  five  per  cent  solution. 

8.  Sulphate  of  copper  ;  a  five  per  cent  solution. 

9.  Chlorid  of  zinc  ;  a  ten  per  cent  solution. 

10.  Sulphur  dioxid  ;  exposure  for  at  least  twelve  hours  to  an  at- 
mosphere containing  at  least  four  volumes  per  cent  of  this  gas  in  the 
presence  of  moisture. 

The  committee  would  make  the  following  recommendations  with 
reference  to  the  practical  application  of  these  agents  for  disinfecting 
purposes :  — 

For  Excreta.—  (a)  In  the  sick  room:  — 

1.  Chlorid  of  lime,  four  per  cent. 
In  the  absence  of  spores:  — 

2.  Carbolic  acid  in  solution,  five  per  cent. 

3.  Sulphate  of  copper  in  solution,  five  per  cent. 
(6)  In  privy  vaults:  — 

1.  Mercuric  chlorid  in  solution,  1  :  500. 

2.  Carbolic  acid  in  solution,  five  per  cent. 

(c)  For  the  disinfection  and  deodorization  of  the  surface  of  masses 
of  organic  material  in  privy  vaults,  etc. :  — 

Chlorid  of  lime  in  powder,  or  freshly  burned  quicklime. 

For  Clothing,  Bedding,  etc.  —  (a)  Soiled  underclothing,  bed 
linen,  etc. 

1.  Destruction  by  fire,  if  of  little  value. 

2.  Boiling  for  at  least  half  an  hour. 

3.  Immersion  in  a  solution  of  mercuric  chlorid  of  the  strength  of 
1  :  2,000  for  four  hours. 

4.  Immersion  in  a  two  per  cent  solution  of  carbolic  acid  for  four 
hours. 


DISINFECTANTS.  379 

(6)  Outer  garments  of  wool  or  silk,  and  similar  articles,  which  would 
be  injured  by  immersion  in  boiling  water  or  in  a  disinfecting  solution:  — 

1.  Exposure  in  a  suitable  apparatus  to  a  current  of  steam  for  ten 
minutes. 

2.  Exposure  to  dry  heat  at  a  temperature  of  110  degrees  C.  (230  de- 
grees F. )  for  two  hours. 

(c)  Mattresses  and  blankets  soiled  by  the  discharges  of  the  sick:  — 

1.  Destruction  by  fire. 

2.  Exposure  to  superheated  steam,  105  degrees  C.  (221  degrees  F.), 
for  ten  minutes.     (Mattresses  to  have  the  cover  removed  or  freely  ex- 
posed.) 

3.  Immersion  in  boiling  water  for  half  an  hour. 

Furniture  and  Articles  of  "Wood,  Leather,  and  Porcelain.  — 
Washing,  several  times  repeated  with :  — 

1.   Solution  of  carbolic  acid,  two  per  cent. 

For  the  Person.  —  The  hands  and  general  surface  of  the  body  of 
attendants  of  the  sick,  and  of  convalescents,  should  be  washed  with:  — 

1.  Solution  of  chlorinated  soda  diluted  with  nine  parts  of  water, 
1  :10. 

2.  Carbolic  acid;  two  per  cent  solution. 

3.  Mercuric  chlorid,  1  :  1,000. 

For  the  Dead.  —  Envelop  the  body  in  a  sheet  thoroughly  saturated 
with :  — 

1.  Chlorid  of  lime  in  solution,  four  per  cent. 

2.  Mercuric  chlorid  in  solution,  1  :  500. 

3.  Carbolic  acid  in  solution,  five  per  cent. 

For  the  Sick-Room.  —  (a)  While  occupied,  wash  all  surfaces 
with:  — 

1.  Mercuric  chlorid  in  solution,  1  : 1,000. 

2.  Carbolic  acid  in  solution,  two  per  cent. 

(6)  When  vacated,  fumigate  with  sulphur  dioxid  for  twelve  hours, 
burning  at  least  three  pounds  of  sulphur  for  every  thousand  cubic  feet 
of  air  space  in  the  room  ;  then  wash  all  surfaces  with  one  of  the  above- 
mentioned  disinfecting  solutions,  and  afterward  with  soap  and  hot 
water  ;  finally  throw  open  doors  and  windows,  and  ventilate  freely." 


APPENDIX   C. 


TABLE  OF  THE  BONES. 


HEAD  (22)   , 


Skull  (8) 


Face  (14) 

CERVICAL  REGION  (8) 
THORAX  (37) 

UPPER  EXTREMITIES  (64) 

LUMBAR  REGION  (5) 
PELVIS  (4) 

LOWER  EXTREMITIES  (60) 


Frontal  (forehead). 

2  Temporal  (temples). 

2  Parietal  (side). 

Occipital  (posterior  base). 

Sphenoid  (base). 

Ethmoid  (base  of  nose). 

2  Superior  Maxillse  (upper  jaw). 

2  Nasal  (bridge  of  nose). 

2  Malar  (cheek). 

2  Lacrymal  (corner  of  orbit) . 

2  Turbinated  (within  nostrils). 

2  Palate  (posterior  hard  palate). 

Vomer  (nasal  partition). 

Inferior  Maxilla  (lower  jaw). 

7  Cervical  Vertebras  (neck). 
Hyoid  Bone  (base  of  tongue). 

14  True,  6  False,  4  Floating  Ribs. 
12  Thoracic  Vertebrae  (back). 
Sternum. 


Shoulder 


Arm 


Hand 


Clavicle  (collar-bone). 
Scapula  (shoulder-blade), 
Humerus  (arm). 
Radius,  Ulna  (fore-arm). 
8  Carpal  (wrist). 
5  Metacarpal  (palm). 
14  Phalanges  (fingers). 


5  Lumbar  Vertebras  (loins). 

2  Innominata. 

Sacrum. 

Coccyx. 


Thigh 
Leg 

Foot 
380 


Femur. 

Patella  (knee-pan). 
Tibia  (large  bone). 
Fibula  (outer  bone). 
7  Tarsal  (instep,  heel). 
5  Metatarsal  (arch). 
14  Phalanges  (toes). 


VITAL    STATISTICS.  381 

Daily  Excretions.  —  Sweat,  from  1.5  Ibs.  to  4.5  Ibs.  ;  urea,  about 
1  oz.  ;  organic  matter  exhaled,  3  grains  ;  urine,  53  oz. 

"Of  the  entire  excreta,  32  per  cent  pass  off  by  the  breath  ;  17  per 
cent  by  the  skin  ;  46.5  per  cent  by  the  kidneys  ;  4.5  per  cent  by  the 
alimentary  canal." — CUTTER. 

Number  of  Sweat  Glands.  —  The  number  of  sweat  glands  may 
be  as  high  as  3,500  in  a  square  inch,  and  the  average  is  estimated  at 
2,800  per  square  inch  ;  as  there  are  about  2,500  square  inches  of  body 
surface,  it  is  readily  computed  that  there  are  several  millions  of  sweat 
glands. 

Number  of  Hairs  on  the  Human  Head.  —  The  average  number 
of  hairs  on  the  head  is  120,000.  They  are  set  obliquely,  and  are  con- 
trolled by  muscles  so  that  they  may  be  made  to  stand  erect,  or  nearly  so, 
under  the  influence  of  certain  emotions,  as  fear,  anger,  etc. 

Huxley  and  others  have  classified  the  races  of  men  according  to  the 
hair,  into  the  Ulotrichi,  or  crisp  or  woolly  haired  division,  including 
the  negroes,  bushmen,  etc.  ;  and  Leiotrichi,  or  smooth-haired,  sub- 
divided into  the  Australioid,  the  Mongoloid,  the  Xanthochroic,  and  the 
Melanochroic. 

In  Europeans  the  hair  is  oval  in  cross-section  ;  in  the  Japanese 
and  Chinese  it  is  circular. 

Circulation.  —  Rate  of  blood  flow  :  in  the  large  arteries,  from  12  to 
16  inches  a  second  ;  in  the  caval  veins,  about  4  inches  a  second  ;  in  the 
capillaries,  from  1  inch  to  1.5  inches  a  minute.  A  portion  of  the  blood 
makes  the  complete  circulation  (in  a  horse)  in  less  than  half  a  minute. 
This  is  found  by  putting  some  readily  detected  chemical  into  one  jugular 
vein,  and  noting  how  soon  it  appears  in  the  other  jugular  vein.  The 
time  necessary  for  all  the  blood  to  pass  through  the  heart  is  estimated 
as  follows  :  Each  ventricle  pumps  about  six  ounces  of  blood  at  each 
stroke.  At  this  rate  thirty  strokes,  25  to  50  seconds  (or  less),  would 
have  pumped  all  the  blood  in  the  body.  Still,  some  of  the  blood  (from 
the  shorter  circuits)  may  have  been  pumped  twice,  and  some  (from  the 
longer  routes)  may  not  yet  have  been  around  once.  And  since  the 
total  amount  of  blood  has  been  only  approximately  determined,  these 
figures  are  not  very  accurate. 

Number  of  blood  corpuscles  to  the  cubic  inch,  about  83,000,000. 

Dr.  Tanner's  Forty  Days'  Fast  (Newspaper  Account).  No 
Food  but  Water  Taken.  —  When  Dr.  Tanner  came  to  New  York 
from  Minnesota  he  weighed  184  pounds.  He  was  six  weeks  making  ar- 


382 


VITAL   STATISTICS. 


rangements  for  his  fast;  and  when  he  began  his  experiment  his  weight 
was  157£  pounds.  lie  weighed  121J  pounds  on  the  day  his  fast  ended. 
He  had  therefore  lost  62^  pounds  since  he  came  to  the  city,  and  36 
pounds  since  he  began  his  fast.  Dr.  Hammond,  the  well-known  New 
York  physician  whose  assertion  that  a  forty  days'  fast  was  a  physical 
impossibility  led  Dr.  Tanner  to  make  the  attempt,  came  out  in  a  card 
in  the  New  York  papers  declaring  that  he  believed  the  fast  had  been 
fairly  conducted. 

On  each  day  of  his  fast  Dr.  Tanner  weighed  as  follows  :  — 


DAY. 

1st  

POUNDS. 

157£ 

DAY.                        P( 

25th  

3d  

153 

26th  

5th  

27th  

7th  

1434 

28th  

Hth  

,  139| 

29th  

13th  

30th  

14th  

133 

31st  

16th  

132 

32d  o  

17th  (8  30  P  M  )  . 

133,| 

33d  

17th  (HAM)  . 

34th  

18th 

1364 

35th  

19th   .... 

136 

36th  

20th  (4  P  M  )  .  . 

,  1354 

37th  

20th  (5AM) 

.  .  135 

38th  

135 

39th  

22d  

,  1334 

40th  

26th  . 

,  1324 

1291 

130 

128 

127i 

126i 

126i 


125i 


121i 


Cavities  of  the  Body.  —  1.  Mucous  cavities  (open  to  the  external 
air).  Digestive  tube,  respiratory  passages,  genito-urinary  passages,  ex- 
ternal and  middle  ear,  etc. 

2.  Serous  cavities  (closed).     They  may  all  be  said  to  be  lymph  cav- 
ities.    They  are  the  lymph  spaces  throughout  the  body,  and  the  large 
spaces,  called  the  pleural  cavity  around  the  lungs,  the  pericardial  cavity 
around  the  heart,  the  peritoneal  cavity  in  the  abdomen,  the  arachnoid 
cavity  around  the  brain,  and  a  similar  one  along  the  spinal  cord. 

3.  Synovial  cavities  in  the  joints. 

4.  Blood  cavities,  —  the  inside  of  the  heart  and  blood  tubes. 

5.  Secretion  cavities,  —  the  cavities  and  tubes  from  the  glands  ;  for 
example,  the  bile  sac  and  its  duct. 

6.  Bone  cavities. 


VITAL   STATISTICS. 


383 


LOSSES  OF  THE  TISSUES  DURING  STARVATION. 
(FROM  EXPERIMENT  ON  A  CAT.) 


Fat loses  93  per  cent. 


Blood  .  .  . 
Spleen  .  .  . 
Pancreas  .  . 
Stomach  .  . 
Pharynx,  gullet 
Skin  .... 
Kidneys .  .  . 
Liver  .... 


75 
71 
64 
39 
34 
33 
31 
52 


Heart      .    . 

Intestines    .    .     . 

Muscles  of  locomo- 
tion .... 

Respiratory  appa- 
ratus .  .  . 

Bones      .... 

Eyes 

Nervous  system  . 


loses  44  per  cent. 

"     42  " 

"     42  " 

22  " 

16  " 
10       " 

2  " 


QUANTITY  OF  WATER  IN  1,000  PARTS. 

Teeth  ...» 100  Bile 880 

Bones 130  Milk 887 

Cartilage 550  Pancreatic  juice 900 

Muscles 750  Urine 936 

Ligament 768  Lymph 960 

Brain 789  Gastric  juice 975 

Blood 795  Sweat 986 

Synovia 805  Saliva .    .    .  995 

THE  LOSS  OF  WATER  FROM  THE  BODY. 

From  the  Alimentary  canal  (feces) 4  per  cent. 

"        "    Lungs 20         " 

"        "    Skin  (perspiration) 30 

"        "    Kidneys  (urine) 46         " 

ELEMENTS  IN  THE    HUMAN  BODY. 

Oxygen 72.0  Chlorin 085 

Carbon 13.5  Fluorin 08 

Hydrogen 9.1  Potassium 026 

Nitrogen 2.5  Iron 01 

Calcium 1.3  Magnesium .0012 

Fosforus 1.15  Silicon 0002 

Sulfur 147  Copper,  lead,  aluminum   .     (traces) 

Sodium 1  100. 

DAILY  RATION  OF  A  U.   S.  SOLDIER  DURING  THE  LATE  WAR. 

Bread  or  flour 22        oz. 

Fresh  or  salt  beef  (or  pork  or  bacon  12  oz.) 20         " 

Potatoes  (three  times  a  week)     . 16         " 


384 


VITAL   STATISTICS. 


Rice 

Coffee  (or  tea  0-.24  oz.) 

Sugar 

Beans 

Vinegar      

Salt   . 


1.6 
1.6 
2.4 
.114 
.32 
.16 


gill. 


COMPOSITION  OF  FOODS. 


WATER.       PBOTEIDS.          FATS. 


Beef,  lean 72 

Beef,  fat     .....  51 

Mutton,  lean  ....  72 

Mutton,  fat     ....  53 

Veal  , 63 

Pork,  fat 39 

Poultry 74 

Whitefish 78 

Salmon 77 

Eels  (rich  in  fat)     .     .  75 

Oysters 75.7 


Milk  .... 
Buttermilk  . 
Cream  .  .  . 
Cheese,  full  . 
Cheese,  skirn  . 
Eggs,  white  . 


88 
66 
36 
44 

78 


Eggs,  yelk 52 


Bread 
Flour . 


19.3 
14.8 
18.3 
12.4 
16.5 

9.8 
21 
18.1 
16.1 

9.9 
11.7 

4.1 

4.1 

2.7 

28.4 

44.8 

20.4 

16 

8.1 
10.8 


3.6 

29.8 

4.9 

31.1 

15.3 

48.9 

3.8 

2.9 

5.5 

13.8 

2.4 

3.9 
.7 

26.7 
31.1 

6.3 

30.7 

1.6 
2 


COMPOSITION  OF  THE  BLOOD. 


Water 
Solids  - 


OARBO- 

IM  m:\TKS. 


Corpuscles 

Proteids  (of  serum)    .     . 
Fibrin  (of  clot)      .     .     . 
Fatty  matters  (of  serum) 
Inorganic  salts      .     .     . 
Gases,  urea,  kreatin,  etc. 


SUGAR. 
5.2 
6.4 

2.8 


STARCH. 
51 

70.8 


130 
70 
2.2 
1.4 
6.0 
6.4 


SALTS 
5.1 

4.4 

4.8 
3.5 
4.7 
2.3 
1.2 
1.0 
1.4 
2.7 
2.7 

.8 

.8 
4.9 
4.5 
4.9 
1.6 
1.3 

2.3 

1.7 


784 


216 
1000 


VITAL    STATISTICS.  885 

COMPOSITION  OF  GASTRIC  JUICE. 

Water 99.44 

Solids  — 

Pepsin, .319 

Salts 218 

Hydrochloric  acid 02 

.557 
100 

Fluids  of  the  Body  (FORD).  —  1.  Circulating  fluids, — chyle, 
lymph,  blood. 

2.  Fluids  for  digestion,  —  saliva,  gastric  juice,  pancreatic  juice,  bile, 
intestinal  juice. 

3.  Fluids  of  closed  cavities,  —  of  the  arachnoid,  pleural,  pericardial, 
and  peritoneal  sacs,  of  joints,  of  the  eye  and  ear,  and  of  cells. 

4.  Secretions  for  protection,  —  cerumen  or  wax,  tears,  fluid  of  mucous 
membranes,  oily  fluids  on  the  surface  of  the  body. 

5.  Fluids  for  discharge,  —  intestinal  secretion,  renal  or  kidney  se- 
cretion, perspiration,  vapor  from  the  lungs,  etc. 

Acids  and  Alkalies  of  the  Body.  —  Acids, — gastric  juice,  mu- 
cus, chyme,  contents  of  large  intestine. 

Alkalies,  —  saliva  (or  neutral),  pancreatic  juice,  intestinal  juice, 
bile  (or  neutral),  contents  of  small  intestine,  sweat. 

Amount  of  Digestive  Liquids.  —  The  amount  of  saliva  secreted 
daily  is  estimated  at  from  1  to  3  pints,  of  gastric  juice  from  10  to  20  pints, 
of  bile  from  2  to  3  pints.  The  amount  of  intestinal  and  other  juices  is 
difficult  to  estimate.  But  it  is  readily  seen  that  a  very  large  amount  of 
liquid  is  daily  separated  from  the  blood  to  be  used  in  the  preparation  of 
the  food  for  absorption  into  the  blood.  This  is  to  be  looked  upon  as  an 
investment.  It  is  supposed  to  be  reabsorbed  with  large  returns  in  addi- 
tion to  the  prepared  food ;  and  if  anything  interferes  with  the  absorp- 
tion of  the  food  material,  especially  if  the  secretion  goes  on,  it  is  plain 
that  bankruptcy  will  follow  as  surely  as  in  the  business  world  whenever 
there  is  a  continual  expenditure  without  corresponding  returns.'  The 
condition  known  as  "diarrhea"  illustrates  this  condition,  perhaps,  as 
well  as  any  well-known  condition  of  the  body. 

Specific  Gravity  of  the  Liquids  of  the  Body.  —  As  all  the 
liquids  of  the  body  have  dissolved  and  suspended  in  them  various  salts 
and  other  matters,  they  *are  all  heavier  than  water. 


386 


VITAL   STATISTICS. 


TIME  REQUIRED  FOR  DIGESTION  OF  FOODS  (BEAUMONT). 


HUS.  MIX. 

Pigs'  feet,  soused  (boiled)    . 

00 

Tripe,  soused  (boiled)  .    .    . 

00 

Soup,  barley  (boiled)   .     .     . 

30 

Trout,  salmon,  fresh  (fried) 

30 

Venison  steak  (broiled)    .    . 

35 

Milk  (boiled)  

2 

00 

Cabbage,  with  vinegar  (raw) 

2 

00 

Eggs,  fresh  (raw)     .... 

2 

00 

Apples,  sour,  mellow  (raw)  . 

2 

00 

Milk  (raw)  

2 

15 

Turkey  (roasted)     .... 

2 

30 

Eggs,  fresh  (soft  boiled)  .    . 

3 

00 

Beefsteak  (broiled)      .    .    . 

3 

00 

Mutton,  fresh  (boiled)      .    . 

3 

00 

Soup,  chicken  (boiled)     .    . 

3 

00 

Bread,  corn  (baked)     .    .    . 

3 

15 

Oysters,  fresh  (roasted)    .     . 

3 

15 

Mutton  (roasted)      .     . 
Eggs  (hard  boiled)  .     . 

Eggs  (fried) 3 

Potatoes,  Irish  (boiled)    .     .  3 

Oysters  (stewed)      ....  3 

Beets  (boiled) 3 

Green  corn  andbeans(boiled),  3 

Salmon  (boiled) 4 

Soup,  beef,  vegetables,  and 

bread  (boiled)    ....  4 

Duck,  barn-yard  (roasted)    .  4 

Heart,  animal  (fried)  ...  4 

Pork,  salt  (fried)      ....  4 

Veal  (fried) 4 

Cabbage  (boiled)      ....  4 

Duck,  wild  (roasted)    ...  4 

Pork,  fresh  (roasted)    ...  5 


mis.  MIX. 
.    3      15 
.    3      30 
.     3      30 
.    3      30 
.    3      30 
45 
45 
00 


00 
00 
00 
15 
30 
30 
30 
15 


Tissues  of  the  Body  (FORD.)  —  1.    Osseous, — bones  and  teeth. 

2.  Cartilaginous,  — pure  cartilage  and  nbro-cartilage. 

3.  Fibrous, — white  and  yellow  ;  i.e.,  the  white  firm  and  strong  to 
bind  parts  together,  and  the  yellow  elastic  to  afford  elasticity  and  free- 
dom of  movement. 

4.  Muscular,  —  striated  or  voluntary  muscles,  and  non-striated  or 
involuntary. 

5.  Adipose,  —  fat  cells  and  inclosed  fat. 

6.  Epithelial,  —  epithelium,  epidermis,  hair,  and  nails. 

7.  Nervous,  —  cerebro- spinal  and  sympathetic. 


WEIGHT  OF  THE  PARTS  OF  THE  BODY  (HUXLEY). 
(OF  A  MAN  WEIGHING  154  LBS.) 

Muscles  and  their  appurtenances 

Skeleton 

Skin    .  


Fat 

Brain 

Thoracic  viscera  (heart  10  oz.)  . 
Abdominal  viscera  (liver  4  Ibs.) 
Blood  (that  can  be  withdrawn) 


68 
24 
10.5 
28 

3 

2.5 
11 

7 

154 


Ibs. 


VITAL   STATISTICS. 


387 


DAILY  INCOME  AND   EXPENDITURE   OF  THE  BODY. 


Solid  food 8,000  grains 

Water 37,650      " 

Oxygen 13,000      " 

58.650 
(3,308  grams,  or  about  8.33  Ibs.) 


EXPENDITURE. 

Lungs 20,000  grains 

Skin 11,750      " 

Kidneys 24,100      " 

Intestines 2,800      " 

58,650 


MEASUREMENTS   OF  TISSUES   (KIRKE). 

AVERAGE   SIZE   IN   FRACTIONS   OF  AN   INCH. 


WIDTH. 

LENGTH. 

A.ir  cells  .    .                       . 

1    to  J 

7(7  lu  30 

Blood  cells  red 

~J  •*• 

j 

s^Tnr 

less.  Yo^ffO  0 

Blood  cells,  colorless    .     .     . 

r$W 

Capillaries  . 

i     +      i 

^000    l°  T  2  0  ^ 

Cilia    

1          ,            i 

30^50  l°^500 

Cones  of  retina  at  yellow  spot 

T^tiiyo  to  nriinf 

Fat  cells  

Tl_    tO  -TTt-rr 

500     "  ¥  0  <T 

Gastric  glands      

3-oo  toTmr 

A  t0  A 

Muscle  fiber,  striated  .    .    . 

•sfa  to  ?£(T 

li  inches. 

Muscle  fiber,  plain  .... 

¥30  0~  to  ^^O  (J 

s£(J  to  ?^T7 

Nerve  cells,  brain     .... 

-solo  o  to  B^ 

Nerve  fibers,  medullated  .     . 

T^O  0  to  T5W 

Nerve  fibers,  non-medullated 

^oVo   to  3(lV(F 

Papillae  of  skin    

V&TJ  to  TUU 

Villi 

i     to  -»•* 

1      tO  4r 

250           70 

50          ¥ 

The  size  and  various  pigmentations  of  the  brain  are  finely  shown  in 
the  following  : 

2%  of  formaldehyde  (=  5%  formalin)  .     .    89 

95%  alcohol 10 

sodium  chlorid 1 


388  VITAL   STATISTICS. 


TO  SHOW  THE  ACTION  OF  CILIA. 

Kill  a  frog,  and  destroy  the  brain  and  spinal  cord  as  directed  on  p.  37. 
Lay  the  frog  on  its  back  ;  divide  the  lower  jaw  longitudinally,  and  con- 
tinue the  cut  as  far  as  the  stomach.  Pin  the  flaps  out  to  the  sides,  thus 
laying  bare  the  roof  of  the  mouth  and  gullet.  If  the  lining  of  the  mouth 
seems  dry,  moisten  it  with  "saline  solution."  Cut  some  cork  fine,  like 
sawdust,  and  drop  a  little  of  it  on  the  roof  of  the  mouth  between  the 
eyes.  The  current  of  mucus,  caused  by  the  vibration  of  the  cilia,  carries 
the  particles  toward  the  stomach.  Snip  off  a  little  of  this  ciliated  lining 
and  mount  in  saline  solution,  and  examine  under  a  high  power  of  a 
good  microscope.  Or  snip  off  a  little  of  the  margin,  or  scrape  a  little 
off  the  surface  of  the  gill  of  a  clam,  and  examine  as  above. 


GLOSSARY. 


Albumen  (al-bu'-meri}.     The  white  of  an  egg. 

Albumin  (_al-bu' -miri) .  A  proteid  substance,  the  chief  constituent  of 
the  body.  Its  molecule  is  highly  complex,  and  varies  widely  within 
certain  limits  in  different  organs  and  in  different  conditions. 

Albuminuria  (al-bu'-mi-nu'-ri-a}.  The  presence  of  albumin  in  the  urine, 
indicating  changes  in  the  blood  or  in  the  kidneys. 

Amylopsin  (am-i-lop'-sin) .     A  ferment  said  to  exist  in  pancreatin. 

Anabolism  (an-ab'-o-lizm}.  Synthetic  or  constructive  metabolism. 
Activity  and  repair  of  function  ;  opposed  to  katabolism. 

Arbor  Vitae  (ar'-6or  m'-te}.  A  term  applied  to  the  branched  appear- 
ance of  a  section  of  the  cerebellum. 

Argon  (ar'-firon).  A  newly  discovered  element  similar  to  nitrogen 
(found  in  the  air). 

Arytenoid  (ar-i-te'-noid} .  Resembling  the  mouth  of  a  pitcher,  as  the 
arytenoid  cartilages  of  the  larynx. 

Atlas  (at'-las}.  The  uppermost  of  the  cervical  vertebrae  (from  the 
mythical  Atlas  who  supported  the  Earth). 

Auricle  (aw'-ri-kl}.  The  auricles  of  the  heart  are  the  two  cavities  be- 
tween the  veins  and  the  ventricles.  Also,  the  pinna  and  external 
nieatus  of  the  ear. 

Axis  (ak'-sis).  The  second  cervical  vertebra,  on  which  the  head,  with 
the  atlas,  turns. 

Bacterium  (bak-te'-ri-um'),  pi.  bacteria.  A  genus  of  microscopic  fungi 
characterized  by  short,  linear,  inflexible,  rod-like  forms  —  without 
tendency  to  unite  into  chains  or  filaments. 

Biceps  (bi'-seps}.     Biceps  brachii,  the  flexor  of  the  arm. 

Bicuspid  (bi-kus'-pid^) .  Having  two  points  ;  the  bicuspid  or  premolar 
teeth ;  the  bicuspid  valve,  between  the  left  auricle  and  the  left  ven- 
tricle. 

Brachial  (braf-ke-al  or  brak'-i-al}.     Pertaining  to  the  arm. 

389 


390  GLOSSARY. 

Bronchus  (brong' -kits'),  pi.  bronchi.  The  two  tubes  into  which  the  tra- 
chea divides  opposite  the  third  thoracic  vertebra,  called  respectively 
the  right  and  left  bronchus. 

Caffein  (kaf-e-in).  An  alkaloid  that  occurs  in  the  leaves  and  beans  of 
the  coffee-tree,  in  Paraguay  tea,  etc. 

Canaliculus  (kan-a-lik'-u-lus),  pi.  canaliculi.  The  crevices  extending 
from  lacunae,  through  which  nutrition  is  conveyed  to  all  parts  of 
the  bone. 

Canine  (ka-riin'  or  ka'-nln").  The  conical  teeth  between  the  incisors 
and  the  premolars. 

Capillary  (kap'-i-la-ri  or  ka-pil'-a-ri).  A  minute  blood-tube  connecting 
the  smallest  ramification  of  the  arteries  with  those  of  the  veins. 

Capsule  (kap'-sul).  A  tunic  or  bag  that  incloses  a  part  of  the  body  or 
an  organ. 

Carbohydrate  (kar-bo-hi'-drat).  An  organic  substance  containing  six 
carbon  atoms  or  some  multiple  of  six,  and  hydrogen  and  oxygen  in 
the  proportion  in  which  they  form  water;  that  is,  twice  as  many 
hydrogen  as  oxygen  atoms.  Starches,  sugars,  and  gums  are  carbo- 
hydrates. 

Cardiac  (kar'-di-ak}.     Pertaining  to  the  heart. 

Carotid  (ka-rot'-id}.     The  principal  right  and  left  arteries  of  the  neck. 

Carpus  (kar'-pus).     Belonging  to  the  wrist;  as  the  carpal  bones. 

Cartilage  (kar'-ti-laj').     Gristle  of  various  kinds,  articular,  etc. 

Casein  (ka'-se-in').  A  derived  albumin,  the  chief  proteid  of  milk,  pre- 
cipitated by  acids  and  by  rennet  at  40°C. 

Cecum  (se'-fcwm).  The  large  blind  pouch  or  cul-de-sac,  in  which  the 
large  intestine  begins. 

Centrum  (sen'-trum}.  The  center  or  middle  part ;  the  body  of  a  verte- 
bra, exclusive  of  the  bases  of  the  neural  arches. 

Cerebellum  (ser-e-bel'-um).  The  inferior  part  of  the  brain,  lying  below 
the  cerebrum. 

Cerebrum  (ser'-e-&rwm).  The  chief  portion  of  the  brain,  occupying  the 
whole  upper  part  of  the  cranium. 

Cervical  (ser'-vi-kal).     Pertaining  to  the  neck,  as  cervical  vertebrae. 

Chordae  tendineae  (kor'-de}.  The  tendinous  cords  connecting  the 
fleshy  columns  of  the  heart  with  the  auriculo-ventricular  valves. 

Choroid  (ko'-roid).  The  second  or  vascular  coat  of  the  eye,  continu- 
ous with  the  iris  in  front,  and  lying  between  the  sclerotic  and  the 
retina. 


GLOSSARY.  391 

Chyle  (kll).  The  milk-white  fluid  absorbed  by  the  lacteals  during  di- 
gestion. 

Chyme  (klni).  Food  that  has  undergone  gastric  digestion,  and  has  not 
yet  been  acted  upon  by  the  biliary,  pancreatic,  and  intestinal 
secretions. 

Cilium  (siT-i-wm),  pi.  cilia.  The  eyelashes  ;  also  the  hair-like  appen- 
dages of  certain  epithelial  cells,  whose  function  is  to  propel  fluid 
or  particles  along  the  passages  that  they  line. 

Ciliary  (sil'-i-a-ri).  Pertaining  to  the  eyelid  or  eyelash  ;  also  by  ex- 
tension to  the  ciliary  apparatus  or  the  structure  related  to  the 
mechanism  of  accommodation.  Pertaining  to  the  cilia. 

Circumvallate  (sir-kum-val'-at*).  Surrounded  by  a  wall  or  prominence, 
as  the  circumvallate  papillae  on  the  tongue. 

Clavicle  (klav'-i-kl).     The  collar-bone. 

Coccyx  (kok'-siks).  The  last  bone  of  the  spinal  column,  formed  by  the 
union  of  four  rudimentary  vertebrae. 

Cochlea  (kok'-le-a}.  A  cavity  of  the  internal  ear,  resembling  a  snail- 
shell. 

Conjunctiva  (kon-jungk-tl'-va}.  The  mucous  membrane  covering  the 
anterior  portion  of  the  globe  of  the  eye,  reflected  on,  and  extending 
to,  the  free  edge  of  the  lids. 

Corpus  Arantii  (kor'-pus).  The  tubercles,  one  in  the  center  of  each 
segment  of  the  semilunar  valves. 

Corpuscle  (kor'-pus-l}.  A  name  loosely  applied  to  almost  any  small, 
rounded  or  oval  body,  as  the  blood  corpuscles. 

Cortex  (kor'-teks*).  Bark.  The  outer  layer  of  gray  matter  of  the  brain  ; 
the  outer  layer,  cortical  substance,  of  the  kidney. 

Cricoid  (krl'-koid}.  Ring-shaped,  as  the  cricoid  cartilage  of  the 
larynx. 

Dentine  (deri-tin}.  The  ivory-like  substance  constituting  the  bulk  of 
the  tooth,  lying  under  the  enamel  of  the  crown  and  the  cement 
of  the  root. 

Diabetes  (dl-a-be' -tez} .  The  name  of  two  different  affections,  diabetes 
mellitus,  or  persistent  glycosuria,  and  diabetes  insipidus,  or  polyu- 
ria,  both  characterized,  in  ordinary  cases,  by  an  abnormally  large 
discharge  of  urine.  The  former  is  distinguished  by  the  presence 
of  an  excessive  quantity  of  sugar  in  the  urine. 

Dialysis  (di-al'-i-sis).  The  operation  of  separating  crystalline  from 
colloid  substances  by  means  of  a  porous  diaphragm,  the  former 


392  GLOSSARY. 

passing  through  the  diaphragm  into  the  pure  water  upon  which  the 
dialyzer  rests. 

Digastric  (di-gas'-trik*).  Having  two  bellies,  as  the  digastric  muscle, 
enlarged  near  each  end  and  with  a  tendon  in  the  middle. 

Duodenum  (<.lu-v-(lt~'-nutn).  The  first  part  of  the  small  intestine,  begin- 
ning with  the  pylorus. 

Emulsion  (e-mui-shun).  Water  or  other  liquid  in  which  oil,  in  minute 
subdivision  of  its  particles,  is  suspended. 

Enamel  (en-am'-el}.     The  hard  covering  of  the  crown  of  a  tooth. 

Endothelium  (en-do-the'-ji-urn).  The  internal  lining  membrane  of 
serous,  synovial,  and  other  internal  surfaces,  the  homolog  of  epi- 
thelium. 

Enzyme  (en'-ziw).  Any  chemic  or  hydrolytic  ferment,  as  distinguished 
from  organized  ferments  such  as  yeast;  unorganized  ferment. 

Epiglottis  (ep-i-ylot'-is).  A  thin  fibro-cartilaginous  valve  that  aids  in 
preventing  food  and  drink  from  passing  into  the  larynx. 

Esophagus  (e-sof-a-gux}.  The  musculo-membranous  tube  extending 
from  the  pharynx  to  the  stomach. 

Eustachian  (u-sta'-ki-an).  Eustachian  tube,  the  tube  leading  from  the 
middle  ear  to  the  pharynx. 

Facet  (fas'-et).  A  small  plane  surface.  The  articulating  surface  of  a 
bone. 

Femur  (/e'-raer).     The  thigh-bone. 

Ferment  (fer'-ment).  Any  micro-organism,  proteid,  or  other  chemic 
substance  capable  of  producing  fermentation,  i.e.,  the  oxidation 
and  disorganization  of  the  carbohydrates. 

Fibrin  (fi'-brin').  A  native  albumen  or  proteid,  a  substance  that,  be- 
coming solid  in  shed  blood,  plasma,  and  lymph,  causes  coagulation 
of  these  fluids. 

Fibula  (fib'-u-la}.  The  smaller  or  splint  bone  in  the  outer  part  of  the 
leg,  articulating  above  with  the  tibia,  and  below  with  the  astraga- 
lus and  tibia. 

Filiform  (fil'-i-form}.     Thread-like,  as  the  filiform  papillae. 

Frontal  (fron'-tal}.     Belonging  to  the  front,  as  the  frontal  bone. 

Fungiform  (fun'-ji-form).  Having  the  form  of  a  mushroom,  as  fungi- 
form  papillae. 

Ganglion  (gang'-gli-on\  pi.  ganglions  or  ganglia.  A  separate  and  semi- 
independent  nervous  center,  communicating  with  other  ganglia  or 
nerves,  with  the  central  nervous  system,  and  peripheral  organs. 


GLOSSARY.  393 

Gastric  (gas'-ink).     Pertaining  to  the  stomach. 

Gelatin  (jel'-a-tin}.  An  albuminoid  substance  of  jelly-like  consistence, 
obtained  by  boiling  skin,  connective  tissue,  and  bones  of  animals 
in  water.  The  glue  of  commerce  is  an  impure  variety. 

Glosso-pharyngeal  (glos'-o-fa-rin'-je-al}.  Pertaining  to  the  tongue  and 
larynx. 

Gluten  (glo'-ten}.  A  substance  resembling  albumin,  and  with  which  it 
is  probably  identified  ;  it  occurs  abundantly  in  the  seeds  of  cereals. 

Glycogen  (gli'-ko-jen).  A  white  amorphous  powder,  tasteless  and  odor- 
less, forming  an  opalescent  solution  with  water,  and  insoluble  in 
alcohol.  It  is  commonly  known  as  animal  starch.  It  occurs  in  the 
blood  and  in  the  liver,  by  which  it  is  elaborated,  and  is  changed  by 
diastasic  ferments  into  glucose. 

Gustatory  (gus'-ta-to-rl}.  Pertaining  to  the  special  sense  of  taste  and 
its  organs. 

Hashish  (hash'-esh).  A  preparation  from  Indian  hemp,  Cannabis  in- 
dica.  It  is  a  powerful  narcotic. 

Haversian  (ha-ver'-zian).  Haversian  canal,  in  bone,  a  central  opening 
for  blood-tubes,  surrounded  by  a  number  of  concentric  rings,  or 
lamellae,  of  bone. 

Hemoglobin  (hem-o-glo'-bin).  A  substance  existing  in  the  corpuscles  of 
the  blood,  and  to  which  their  red  color  is  due. 

Hepatic  (he-pat'-ik).     Pertaining  or  belonging  to  the  liver. 

Hilum  (hi'-lum).  A  small  pit,  scar,  or  opening  in  an  organic  structure  ; 
the  notch  on  the  internal  or  concave  border  of  the  kidney. 

Humerus  (hu'-me-rus}.     The  bone  of  the  upper  arm. 

Humor  (/m'-mor).     Any  liquid,  or  semi-liquid,  part  of  the  body. 

Hyoid  (hi'-oid).  Having  the  form  of  the  letter  U.  The  hyoid  bone 
situated  between  the  root  of  the  tongue  and  the  larynx,  supporting 
the  tongue  and  giving  attachment  to  its  muscles. 

Hypo-glossal  (hi-po-glos'-al}.     Under  the  tongue. 

Iliac  (il'-l-ak}.  Pertaining  to  the  ilium,  or  region  of  the  flanks,  as  iliac 
artery,  vein,  etc. 

Incisor  (m-si'-sor).     The  chisel-shaped  front  teeth. 

Inhibition  (in-hi-bish'-un}.  The  act  of  checking,  restraining,  or  sup- 
pressing ;  any  influence  that  controls,  retards,  or  restrains.  Inhib- 
itory nerves  and  centers  are  those  intermediating  a  modification, 
stoppage,  or  suppression  of  a  motor  or  secretory  act  already  in 
progress. 


894  GLOSSARY. 

Innominate  (i-nom'-i-nafe).  Nameless  ;  a  term  applied  to  several  parts 
of  the  body  to  which  no  other  definite  name  has  been  given,  as  the 
innominate  bone,  artery,  vein,  etc. 

Invertin  (in'-ver-tin).  A  ferment  found  in  the  intestinal  juice,  and  also 
produced  by  several  species  of  plants  ;  it  converts  cane-sugar  in 
solution  into  invert  sugar. 

Jugular  (jo'-gu-lar').     Pertaining  to  the  throat,  as  the  jugular  vein. 

Katabolism  (ka-tab'-o-lizm}.  Analytic  or  destructive  metabolism  ;  a 
physiologic  disintegration  ;  opposed  to  anabolism. 

Lacrymal  (lak'-ri-mal}.  Having  relation  to  the  organs  of  the  secretion, 
transfer,  or  excretion  of  tears. 

Lacuna  (la-ku'-na}.  A  little  hollow  space  ;  especially  the  microscopic 
cavities  in  bone  occupied  by  the  bone  corpuscles,  and  communicat- 
ing with  one  another  and  with  the  haversian  canals  and  the  sur- 
faces of  the  bone  through  the  canaliculi. 

Lamella  (la-mel'-a\  pi.  lamellae.  A  thin  lamina,  scale,  or  plate  ;  of 
bone,  the  concentric  rings  surrounding  the  haversian  canals. 

Larynx  (lar'-inyks}.  The  upper  part  of  the  air  passage  between  the 
trachea  and  the  base  of  the  tongue  ;  the  voice-box. 

Legumin  (le-gu'-min).  A  proteid  compound  in  the  seeds  of  many  plants 
belonging  to  the  natural  order  Leguminosae  (peas,  beans,  lentils, 
etc.). 

Lumbar  (Jura'-frctr),  pertaining  to  the  loins,  especially  to  the  region 
about  the  loins. 

Lymphatic  (lim-fat'-ik}.     Pertaining  to  lymph. 

Lymphatics  (llm-fat'-iks}.     The  tubes  that  convey  lymph. 

Lymphatic  glands.  The  glands  intercalated  in  the  pathway  of  the 
lymphatic  tubes,  through  which  lymph  is  filtered. 

Massage  (ma-sazh'').  A  method  of  effecting  changes  in  the  local  and 
general  nutrition,  action  and  other  functions  of  the  body,  by  rub- 
bing, kneading,  and  other  manipulation  of  the  superficial  parts  of 
the  body  by  the  hand  or  an  instrument. 

Masseter  (mas'-e-ier).  A  chewing-muscle  felt  on  the  angle  of  the 
jaw. 

Medullary  (med'-u-Zd-ri).  Pertaining  to  the  medulla,  or  marrow  ;  re- 
sembling marrow.  Also  pertaining  to  the  white  substance  of  the 
brain  contained  within  the  cortical  envelop  of  gray  matter. 

Mesenteric  (mez-en-ter'-ik}.  Pertaining  to  the  mesentery,  as  artery, 
vein,  etc. 


GLOSSARY.  395 

Mesentery  (mez'-en-ter'i*).  A  fold  of  the  peritoneum  that  connects  cer- 
tain portions  of  the  intestine  with  the  dorsal  abdominal  wall. 

Metabolism  (me-tab'-d-lizrn).  A  change  in  the  intimate  condition  of 
cells  ;  (1)  constructive  or  synthetic  metabolism  is  called  Anabo- 
lism  ;  in  anabolism,  the  substance  is  becoming  more  complex  and 
is  accumulating  force  ;  (2)  destructive  or  analytic  metabolism  is 
called  Katabolism  ;  in  katabolism  there  is  disintegration,  the  mate- 
rial is  becoming  less  complex,  and  there  is  loss  or  expenditure  of 
force. 

Metacarpus  (met-a-kar'-pus').     The  bones  of  the  palm  of  the  hand. 

Matatarsus  (met-a-tar'-sus}.  The  five  bones  of  the  arch  of  the  foot, 
situated  between  the  tarsus  and  the  phalanges. 

Mitral  (mi'-traV).  Resembling  a  miter;  mitral  valve,  with  two  flaps, 
between  the  left  auricle  and  the  left  ventricle. 

Molar  (rao'-Zar).     Mill;  the  grinding-teeth. 

Mucous  (mu'-kus~).     A  term  applied  to  those  tissues  that  secrete  mucus. 

Mucus  (mil'-fcws).  A  viscid  liquid  secretion  of  mucous  membranes, 
composed  essentially  of  mucin,  holding  in  suspension  desquamated 
epithelial  cells,  etc. 

Myosin  (  wi'-o-srn).  A  proteid  of  the  globulin  class,  —  the  chief  proteid 
of  muscle.  Its  coagulation  after  death  causes  rigor  mortis. 

Narcosis  (nar-ko'-sis} .  The  deadening  of  pain,  or  production  of  incom- 
plete or  complete  anesthesia  by  the  use  of  narcotic  agents,  such  as 
anesthetics,  opium,  and  other  drugs. 

Narcotic  {nar-kot'-ic}.     A  drug  that  produces  narcosis. 

Neural  (mi'-raZ).     Pertaining  to  the  nerves. 

Neuroglia  (nu-rog'-li-a).  The  reticulated  framework  or  skeleton-work 
of  the  substance  of  the  brain  and  spinal  cord.  The  term  is  some- 
times abbreviated  to  glia. 

Nucleus  (nu'-kle-us~).  The  essential  part  of  a  typical  cell,  usually  round 
in  outline,  and  situated  in  the  center. 

Occipital  (ok-sip'-i-tal*).  Pertaining  to  the  occiput  or  back  part  of  the 
head,  as  the  occipital  bone. 

Odontoid  (o-don'-toid}.  Resembling  a  tooth  ;  the  tooth-like  process 
(axis)  of  the  second  cervical  vertebra,  on  which  the  atlas  turns. 

Olfactory  (ol-fak'-to-ri).     Pertaining  to  the  sense  of  smell. 

Osmosis  (os-mo'-sis).  That  property  by  which  liquids  and  crystalline 
substances  in  solution  pass  through  porous  septa ;  endosmosis  and 
exosmosis. 


396  GLOSSARY. 

Oxy-hemoglobin  (ok-si-hem-o-glo'-bin).  Hemoglobin  united,  molecule 
for  molecule,  with  oxygen.  It  is  the  characteristic  constituent  of 
the  red  corpuscles  to  which  the  scarlet  color  of  arterial  blood  is 
due. 

Pancreas  (pan'-kre-as}.  A  large  racemose  gland  lying  transversely 
across  the  dorsal  wall  of  the  abdomen.  It  secretes  a  clear  liquid 
for  the  digestion  of  proteids,  fats,  and  carbohydrates.  The  sweet- 
bread of  animals,  vulgarly  called  the  "belly  sweet-bread"  in  con- 
tra-distinction  to  the  thymus,  or  true  sweet-bread. 

Pancreatin  (panf-kre-a-tln}.    The  active  element  of  the  pancreatic  juice. 

Papilla  (pd-pif-a),  pi.  papillae.  Any  soft,  conical  elevation,  as  papillae 
of  the  dermis,  tongue,  etc. 

Papillary  (pap'-i-la-ri}.  Pertaining  to  a  papilla;  papillary  muscles,— 
the  conic  muscular  columns  of  the  heart,  to  which  the  chordae 
tendineae  are  attached. 

Parietal  (pa-rl'-e-tal}.     Pertaining  to  the  walls,  as  the  parietal  bone. 

Parotid  (pa-rot'-id}.     Near  the  ear,  as  the  parotid  salivary  glands. 

Patella  (pa-tel'-a}.     The  knee-pan. 

Peptone  (pep'-lon}.  A  proteid  body  produced  by  the  action  of  peptic 
and  pancreatic  digestion. 

Pericardium  (per-i-kar'-di-um}.  The  closed  membranous  sac  or  cover- 
ing that  envelops  the  heart. 

Periosteum  (per-i-os'-te-um}.  A  fibrous  membrane  that  invests  the 
surfaces  of  the  bones,  except  at  the  points  of  tendinous  and  liga- 
mentary  attachments,  and  on  the  articular  surfaces  where  cartilage 
is  substituted. 

Peristaltic  (per-i-stal'-tik}.  The  peculiar  movement  of  the  intestine 
and  other  tubular  organs,  consisting  in  a  vermicular  shortening 
and  narrowing  of  the  tube,  thus  propelling  the  contents  onward. 
It  is  due  to  the  successive  contractions  of  the  bundles  of  longitudi- 
nal and  circular  muscular  fibers. 

Peritoneal  (per-i-to-ne'-al).     Pertaining  to  the  peritoneum. 

Peritoneum  (per-i-to-ne'-um}.  The  serous  membrane  lining  the  interior 
of  the  abdominal  cavity,  and  surrounding  the  contained  viscera. 
The  peritoneum  forms  a  closed  sac,  but  is  rendered  complex  in  its 
arrangement  by  numerous  foldings  produced  by  its  reflection  upon 
the  viscera. 

Phalanges  (fa-lan'-jez},  plural  of  phalanx  (fd'-langks).  Any  one  of 
the  bones  of  the  fingers  or  toes. 


GLOSSARY.  397 

Pharynx  (far'-inyks^.  The  cavity  back  of  the  soft  palate.  It  commu- 
nicates anteriorly  with  the  posterior  nares,  laterally  with  the  eusta- 
chian  tubes,  ventrally  with  the  mouth,  and  posteriorly  with  the 
gullet  and  larynx. 

Plasma  (plaz'-ma).  The  original  undifferentiated  substance  of  nascent, 
living  matter.  The  fluid  part  of  the  blood  and  lymph. 

Pleura  (pJo'-ra).  The  serous  membrane  which  envelops  the  lungs,  and 
which,  being  reflected  back,  lines  the  inner  surface  of  the  thorax. 

Plexus  (plek'-sus}.  An  aggregation  of  vessels  or  nerves  forming  an 
intricate  net-work. 

Pneumogastric  (nu-mo-gas'-trik}.  Pertaining  conjointly  to  the  lungs 
and  the  stomach,  or  to  the  pneumogastric  or  vagus  nerve. 

Portal  (por'-tal).  Pertaining  to  the  porta  (gate)  or  hilum  of  an  organ, 
especially  of  the  liver,  as  the  portal  vein. 

Postcaval  (post-ka'-val*).  Pertaining  to  the  postcava;  the  postcaval 
vein,  formerly  called  the  inferior  vena  cava,  or  vena  cava  ascendens. 

Precaval  (pre-ka'-vaty.  Pertaining  to  the  precava;  the  anterior  caval 
vein,  formerly  called  the  superior  vena  cava,  or  vena  cava  de- 
scendens. 

Pro  nation  (pro-na'-shun^).     The  turning  of  the  palm  downward. 

Protoplasm  (pro'-to-plazm}.  An  albuminous  substance,  ordinarily  re- 
sembling the  white  of  an  egg,  consisting  of  carbon,  oxygen,  nitro- 
gen, and  hydrogen  in  extremely  complex  and  unstable  molecular 
combination,  and  capable,  under  proper  conditions,  of  manifesting 
certain  vital  phenomena,  such  as  spontaneous  motion,  sensation, 
assimilation,  and  reproduction,  thus  constituting  the  physical  basis 
of  life  of  all  plants  and  animals. 

Ptyalin  (tl'-a-lin}.  An  amylolytic  or  diastasic  ferment  found  in  saliva, 
having  the  property  of  converting  starch  into  dextrin  and  sugar. 

Pulmonary  (pul'-md-na-ri^).     Pertaining  to  the  lungs. 

Pylorus  (pi-lo'-rus}.     The  opening  of  the  stomach  into  the  duodenum. 

Radius  (ra'-di-us}.     The  outer  of  the  bones  of  the  forearm. 

Renal  (re'-nal).     Pertaining  to  the  kidneys. 

Rennin  (ren'-in).  An  enzyme,  or  ferment,  to  whose  action  is  due  the 
curdling  or  clotting  of  milk  produced  upon  the  addition  of  ren- 
net. 

Retina  (ref-i-na).  The  chief  and  essential  peripheral  organ  of  vision; 
the  third  or  internal  coat  or  membrane  of  the  eye,  made  up  of  the 
end  organs  or  expansion  of  the  optic  nerve  within  the  globe. 


398  GLOSSARY. 

Sacrum  (.sfi'-Arrww).     A  curved  triangular  bono,  composed  of  five  con- 
solidated vertebrae,  wedged  between  the  two  iliac  (pelvic)  bones, 

and  forming  the  dorsal  boundary  of  the  pelvis. 
Scapula  (akap'-u-la).     The  shoulder-blade. 
Sciatic  (sl-at'-ik}.     Pertaining  to  the  ischium;  the  sciatic  nerve,  the 

main  nerve  of  the  thigh. 
Sclerotic  (skle-rot'-ik).     Hard,  indurated;  pertaining  to  the  outer  coat 

of  the  eye. 
Semilunar  (sem-i-lu'-nar).     Resembling  a  half-moon  in  shape;  semilu- 

nar  valves,  pocket-like  valves  at  the  beginning  of  the  aorta  and 

pulmonary  artery. 
Serous  (se'-rws).     Pertaining  to,  characterized  by,  or  having  the  nature 

of,  serum. 
Serum  (se'-rwm).     The  yellowish  fluid  separating  from  the  blood  after 

the  coagulation  of  the  fibrin. 

Solar  plexus  (so'-lar).     Solar,  with  radiations  resembling  the  sun. 
Sphincter  (sfinyk'-ter}.     A  muscle  surrounding  and  closing  an  orifice. 
Splenic  (splen'-ik).     Pertaining  to  the  spleen. 
Steapsin  (step'-sin}.     A  diastasic  ferment  which  causes  fats  to  combine 

with  an  additional  molecule  of  water  and  then  split  into  glycerine 

and  their  corresponding  acids. 
Sternum  (ster'-num}.     The  breast-bone. 
Subclavian  (sub-kla'-vi-an}.     Situated  under  the  collar-bone  ;    subcla- 

vian  artery  and  vein. 
Sublingual  (sub-liny '-ywal}.     Lying  beneath  the  tongue,  as  sublingual 

gland. 
Submaxillary  (sub-mak'-si-la-ri}.     Lying  beneath  the  lower  maxilla,  as 

submaxillary  salivary  gland. 

Supination  (su-pi-na'-shun).     The  turning  of  the  palm  upward. 
Synovia  (si-no' -vi-a).     The  lubricating  liquid  secreted  by  the  synovial 

membranes  in  the  joints. 

Tarsus  (tar'-sus').     The  instep,  consisting  of  seven  bones. 
Temporal  (tem'-pd-ral).     Pertaining  to  the  temples,  as  temporal  artery, 

vein,  muscle,  etc. 
Tetanus  (tet'-a-nus}.     A  spasmodic  and  continuous  contraction  of  the 

muscles,  causing  rigidity  of  the  parts  to  which  they  are  attached. 
Thein  (the'-in').     An  alkaloid  found  in  tea. 

Theobromin  (the-o-bro'-min').     A  feeble  alkaloid  obtained  from  cacao- 
butter  ;  the  essential  substance  found  in  cocoa  and  chocolate. 


GLOSSARY.  899 

Thyroid  (thi'-roid').  Shield-shaped,  as  the  thyroid  cartilage  of  the 
larynx. 

Tibia  (tib'-i-a).  The  larger  (inner)  of  the  two  hones  of  the  log,  com- 
monly called  the  shinbone. 

Trachea  (trd-ke'-a  or  tra'-ke-a}.     The  windpipe. 

Triceps  (tri'-seps}.  Triceps  of  the  arm,  the  extensor  of  the  arm,  lying 
along  the  back  of  the  humerus. 

Tricuspid  (tri-kus'-pid^.  Having  three  cusps  or  points,  as  thetricuspid 
valve. 

Trypsin  (trip'-sin}.     The  proteolytic  ferment  of  pancreatic  juice. 

Ulna  (w/'-na).     The  larger  (inner)  of  the  two  bones  of  the  forearm. 

Ureter  (w-re'-ier).  The  tube  conveying  the  urine  from  the  pelvis  of  the 
kidney  to  the  bladder. 

Vaso-constrictor  (vas'-o-kon-strik'-tor).  Causing  a  constriction  of  the 
blood-vessels. 

Vaso-dilator  (vas'-b-di-la'-tor}.  Pertaining  to  the  positive  dilating  mo- 
tility  of  the  non-striated  muscles  of  the  vascular  system. 

Vaso-motor  (vas-o-mo'-tor).  Serving  to  regulate  the  tension  of  the 
blood-vessels,  as  vaso-motor  nerves  ;  including  vaso-dilator  and 
vaso-constrictor  mechanisms. 

Ventricle  (ven'-tri-kl}.  Applied  to  certain  structures  having  a  bellied 
appearance.  The  cavities  of  the  heart  from  which  the  blood  is 
forced  out  through  the  arteries. 

Vesicle  (ves'-i-kl}.  A  small,  membranous,  bladder-like  formation,  as 
air  vesicle. 

Villus  (vil'-us\  pi.  villi.  One  of  the  numerous  minute  vascular  projec- 
tions from  the  mucous  membrane  lining  the  small  intestine,  for  ab- 
sorbing digested  food. 

Vitreous  (mt'-re-us}.  Glass-like,  as  the  clear,  jelly-like,  vitreous  humor 
of  the  eye. 


INDEX. 


Abdominal  aorta,  69. 

Muscles,  196. 

Organs,  195. 

Viscera,  weight  of,  386. 
Absorption,  219. 

Checking,  232. 

Of  fats,  222. 

Plan  of,  220. 

From  the  stomach,  215. 
Accessory  foods,  167. 
Accidents,  328. 
Acetic  acid,  338. 
Acids,  298,  338. 

Acetic,  338. 

Of  the  body,  385. 

Carbolic,  338. 

Carbonic,  341. 

Citric,  338. 

Hydrochloric,  207. 

Medicines,  202. 

Muriatic,  338. 

Nitric,  338. 

Oxalic,  338. 

Prnssic,  338. 

Sulphuric,  338. 

Tartaric,  338. 
Aconite,  340. 
Aero-narcotics,  340. 
Action  of  auricle,  73. 

Heart,  72. 

Heart  of  frog,  72. 

Large  arteries,  76. 

Medium-sized  arteries,  76. 

Saliva,  205. 


Action  of  salivary  glands,  204. 

Valves  of  the  heart,  73,  74. 
Adam's  Apple,  320,  321. 
Adjustment  of  lens  for  distance,  308. 
Afferent  root  of  spinal  nerve,  40. 
After-image,  negative,  312. 

Positive,  312. 
After-pressure,  288. 
Air,  complemental,  117. 

Composition  of,  122. 

Currents  around  stove,  140. 

Effect  of  rain  on,  143. 

Effect  of  snowstorm,  143. 

Reserve,  118. 

Residual,  119. 

Tidal,  117. 

Vesicles,  105, 112, 129. 
Aladdin  oven,  371,  374. 
Albinos,  152. 
Albumen,  168. 
Albuminnria,  245. 
Alcohol,  175,  340. 

Affinity  for  water,  177- 

Binz,  186. 

Brnnton,  274. 

And  crime,  176, 178. 

Cumulative  effects  of,  175. 

Effect  on  circulation,  93. 

Effects  on  nervous  system,  274. 

And  energy,  176. 

In  the  excretions,  180, 190. 

And  exposure  to  cold,  177. 

Ganle,  182. 

Greely,  184. 


401 


402 


INDEX. 


Alcohol  habit,  176. 

Halliburton,  189. 

As  a  heat  producer,  176. 

Helinholtz,  182. 

Hodge,  182. 

Howell,  180. 

Jenkins,  178. 

And  longevity,  Baer,  188. 

Lusk,  179. 

M'Kendrick,  190. 

And  mountain  climbing,  181. 

Oxidation  of,  in  the  body,  176, 180. 

And  poverty,  176. 

Kobe',  186. 

Smith,  182. 

Snell,  181. 

Stanley,  184. 

In  the  stomach,  179. 

Thompson,  182. 

And  training,  177. 

Woodhull,  184. 

Woodruff,  185. 
Alkalies,  338. 

Of  the  body,  385. 
Alveoli,  105. 
Ammonia,  300,  338. 

Inhalation  of,  330,  341. 
Amount  of  digestive  liquids,  385. 

Urine,  166. 

Amplitude  of  respiration,  299. 
Amylopsin,  207,  218. 
Anabolic  stair,  248. 
Anabolism,  250. 
Anatomy,  definition  of,  5. 
Anesthetics,  278. 
Animal  heat,  restoration  of,  333. 

Irritants,  340. 
Animals,  cold-blooded,  160. 

Warm-blooded, -160. 
Anterior  articulating  process,  349. 
Antidotes  to  poisons,  336,  338-341. 
Antimony,  339. 
Antiseptics,  377. 
Anvil,  317. 


Aorta,  56. 

Abdominal,  69. 

Thoracic,  69. 

Apes,  brain  centers  of,  261. 
Apex  of  heart,  57,  75. 

Lung,  56,  108. 
Apoplexy,  266. 
Apparatus,  injecting,  68. 
Appendicitis,  228. 
Appendicular  skeleton,  346. 
Appendix  vermiformis,  228. 
Aqueous  humor,  303. 
Arbor  vitse,  256. 
Arch  of  aorta,  69. 

Neural,  346. 
Argon,  122. 

Aristotle's  experiment,  273. 
Arsenic,  339. 
Arteries,  54,  70,  71. 

Action  of  large,  76. 

Action  of  medium-sized,  76. 

Bleeding  from,  328. 

Cardiac,  61. 

Carotid,  69,  71. 

Carotid,  bleeding  from,  328. 

Coats  of,  78. 

Coronary,  61. 

Distribution  of,  69,  71. 

Femoral,  bleeding  from,  328. 

Gastric,  69,  71. 

Hepatic,  69,  71,217. 

Iliac,  70,  71. 

Injection  of,  65. 

Mesenteric,  70,  217. 

Muscle  fiber  in,  77,  78. 

Pancreatic,  71. 

Pulmonary,  58. 

Renal,  70,  71,  162. 

Splenic,  69,  71. 

Structure  of,  78,  79. 

Subclavian,  69,  71. 
Articulating  processes,  348,  349. 
Artificial  butter,  357. 
Arytenoid  cartilage,  322. 


INDEX. 


403 


Arytenoirl  muscle,  323. 
Ascending  colon,  228. 
Asiatic  cholera,  145. 
Assimilation,  249. 
Association  fibers,  269,  270. 
Atkinson,  Aladdin  oven,  372,  374. 
Atlas,  350. 
Auditory  meatus,  317. 

Nerves,  255,  259. 
Auricle,  57. 
Auricles,  action  of,  73. 

Contraction  of,  72. 
Automaton,  260. 
Axial  skeleton,  346. 
Axis,  350. 
Axis-cylinder,  34. 

Bacilli,  146. 

Bacillus  tuberculosis,  145. 

Bacon,  370. 

Bacteria,  146. 

Of  disease,  146. 

Of  milk,  149. 

Of  putrefaction,  149. 
Baer,  alcohol  and  longevity,  188. 
Baking-powder,  229. 
Bananas,  229. 
Baryta,  338. 
Base  of  lung,  108. 
Baseball,  237. 
Bath  mits,  233. 
Bathing,  233. 

The  sick,  343. 
Baths,  cold,  233. 

Prolonged,  warm,  234. 
Bayard  Taylor,  hashish,  280. 
Beans,  169,  230. 

Digestibility  of,  360. 
Bear  and  candle,  247. 
Beat  of  heart,  75. 

Of  frog,  72. 
Bee-stings,  330. 
Beef,  168. 

Extracts,  175. 


Beef  tea,  175. 

Beefsteak,  composition  of,  226. 

Beer,  root,  179. 

Beets,  230. 

Belladonna,  278,  340. 

Biceps  muscle,  10. 

Bicuspid  teeth,  200. 

Bicycling,  236. 

Bile,  217. 

Duct,  196. 

Functions  of,  218. 

Sac,  196. 

Bills  of  fare,  367,  375,  376. 
Biriz,  on  alcohol,  186. 
Bismuth,  339. 
Bites  of  cats  and  dogs,  337. 

From  snakes,  337. 
Bitters,  298. 
Bittersweet,  341. 
Blackberries,  230. 
Bladder,  161,  195. 

Muscle  fibers  of,  76. 
Blaikie,  How  to  Get  Strong,  28,  235. 

Sound  Bodies,  28. 
Bleeding  from  arteries,  328. 

Femoral  artery,  328. 

Lungs,  329. 

The  nose,  329. 

Stomach,  329. 

Veins,  329. 
Blind  spot,  310. 
Blindness,  color,  311. 
Blister,  152. 
Blood,  the,  94. 

Amount  of,  97. 

Blister,  152. 

Coagulation  of,  97. 

Color  of,  131. 

Composition  of,  384. 

Corpuscles,  94,  95. 

Distribution  of,  97. 

Frog's,  51. 

Gases  of,  130. 

Poisoning,  145. 


404 


INDEX. 


Blood,  transfusion  of,  103. 

Ventilation  of,  136. 

Work  of,  48. 
Blood-flow,  in  capillaries,  78. 

Experiments  with,  79. 

Rate  of,  84. 
Blood-supply,  of  brain,  263,  265. 

Regulation  of,  76,  87. 
Blue  vitriol,  206,  339. 
Blushing,  86. 
Boats  upsetting,  335. 
Bodily  Exercise,  Lagrange,  239. 
Body  cavities,  382. 
Body,  ledger  account  of,  241. 

And  locomotive,  134. 

And  stove,  134. 

Tissues  of,  386. 
Boiled  milk,  230. 
Boiling  meat,  193. 

Water,  172. 
Bone,  composition  of,  354. 

Forceps,  33,  301. 

Gross  structure  of,  23,  24. 

Hyoid,  322. 

Microscopic  structure  of,  352. 

Study  of  long,  23. 
Bones,  broken,  330. 

Of  the  ear,  317. 

Functions  of,  27. 

Hygiene  of,  355. 

As  levers,  26. 

Table  of,  380. 

Turbinated,  299. 
Bouillon,  175. 
Bowels,  cold  in,  233. 
Boxing,  238. 

Brackett,  Technique  of  Rest,  281. 
Brain,  blood-supply  of,  263,  265. 

Of  cat  or  rabbit,  253. 

Functions,  location  of,  261. 

Ganglia  of,  258. 

Preservation  of,  253,  387. 

Rest,  263. 

And  spinal  cord,  29. 


Brain,  weight  of,  38G. 

Work,  263. 

Workers,  2(54. 
Brainless  dog,  260. 

Frog,  259. 

Pigeon,  259. 
Bran,  170. 
Bread,  composition  of,  226. 

Entire  wheat,  170. 

Hot,  229. 

White,  229. 
Breathing,  hygiene  of,  120. 

Through  the  mouth,  142. 
Broken  bones,  330. 
Bronchi,  57,  105. 
Brunton,  on  alcohol,  274. 
Buds,  taste,  298. 
Bulb,  spinal,  33,  254,  263. 
Burns,  329. 
Butter,  artificial,  357. 

Composition  of,  226. 

Cabbage,  raw,  230. 

Caffein,  175. 

Cake,  229. 

Calcium  carbonate,  173. 

Phosphate,  173. 
Calf,  larnyx  of,  321. 

Muscle  of  frog,  13, 14. 
Caliber  of  arteries,  78,  87,  88. 
Call,  Power  through  Repose,  47,  281. 
Camel's  hump,  246. 
Camphor,  340. 
Canal,  central,  254. 

Haversian,  352. 

Semicircular,  318. 
Canaliculi,  353. 
Candle  and  bear,  247. 

Burning,  125. 

And  energy,  251. 
Cane  sugar,  219. 
Canine  teeth,  200. 
Capacity  of  the  lungs,  117. 
Capillaries,  54. 


INDEX. 


405 


Capillaries,  blood-flow  in,  78. 

Of  lungs,  112. 

Lymph,  98. 

Pulmonary,  105. 

Structure  of,  79. 
Capsule  of  lens,  304. 

Urinary,  165. 
Carbohydrates,  170,  359. 
Carbohydrate  foods,  170,  359. 
Carbolic  acid,  338. 
Carbon  dioxid,  in  the  air,  122. 

In  air  and  breath,  127. 

Generation  of,  124. 

Test  of,  125. 

In  violent  exercise,  135. 
Carbonate  of  calcium,  173. 
Carbonic  acid,  341. 
Carbonic  oxid,  341. 
Care  of  the  ear,  318. 

Of  the  eyes,  312. 

Of  the  sick,  342,  343. 

Of  the  teeth,  202. 
Carnivora,  174. 
Carotid  artery,  69. 

Bleeding  from,  328. 
Carpets,  objections  to,  147. 
Cartilage,  25. 

Arytenoid,  322. 

Cricoid,  322. 

Intervertebral,  350. 

Thyroid,  321. 

Of  windpipe,  55,  107. 
Casein,  167,  168. 
Cataract,  305. 
Cats,  bites  from,  337. 
Cauliflower,  230. 
Caustic  potash,  206. 
Cavities  of  the  body,  382. 

Serous,  102. 
Cavity,  marrow,  24. 

Medullary,  23. 

Neural,  31. 

Peritoneal,  102. 
Cecum,  196,  228. 


Celery,  230. 

Cell,  6. 

Cells,  ciliated,  107. 

Size  of,  387. 
Cellulose,  359. 
Cement  of  tooth,  200. 
Center,  for  hearing,  262. 

For  respiration,  122. 

For  smell,  262. 

For  speech,  262. 

For  vision,  262. 

Of  distinct  vision,  306. 
Centers,  motor,  261. 

Nerve,  of  glands,  155. 

For  sensation,  262. 
Central  canal,  254. 

Fissure,  262. 
Centrum,  346. 
Cereals,  169. 
Cerebellum,  33,  256. 

Functions  of,  263. 
Cerebral  cortex,  261. 
Cerebrum,  33,  255,  256. 

Functions  of,  259. 
Cervical  vertebrae,  349. 
Cesspools,  171,  172. 
Chain,  sympathetic  nerve,  90. 
Changing  underwear,  161. 
Cheese,  169,  229,  370. 

For  dessert,  231. 

Making,  214. 

Chemical  composition  of  bone-  354. 
Chemistry  of  cookery,  372. 

Of  respiration,  123. 
Chewing  gum,  205. 
Chloral,  340. 
Chlorine,  341. 
Chloroform,  341. 
Chlorophyll,  251. 
Chocolate,  175,  229.  * 

Cholera,  Asiatic,  145. 
Chordae  tendineae,  60,  73. 
Choroid  coat,  304. 
Chyle,  223. 


406 


INDEX. 


Chyle,  receptacle  of,  98,  22;>. 
Chyme,  215. 

Composition  of,  21(5. 
Cider,  179. 

Fermentation  of,  145. 
Cilia,  107. 
Ciliary  muscle,  307,  301). 

Processes,  304. 
Circulation  of  blood,  48. 

Of  blood,  effect  of  alcohol  on,  93. 

Of  lymph,  100. 

Plan  of,  85,  131,  242,  243,  244. 

Portal,  217. 

Kate  of,  381. 
Circulating  proteid,  249. 
Circumvallate  papillae,  297. 
Cistern,  171. 
Citric  acid,  338. 
Classification  of  joints,  355. 
Clot,  blood,  97. 
Clothes,  effect  of,  158. 
Clothing,  160. 

Taking  fire,  330. 
Clum,  Inebriety,  275. 
Coagulation  of  blood,  97. 
Coagulum,  97. 
Coat,  choroid,  304. 

Sclerotic,  304. 
Coats  of  artery,  78. 

Of  stomach,  213. 
Coccyx,  350. 
Cochlea,  317. 
Cocoa,  175,  229. 
Codfish,  169. 
Coffee,  173,  175,  230. 

Toast,  230. 

Wheat,  230. 
Colchicum,  340. 
Cold  bath,  233. 

Blooded  animals,  160. 

In  the  bowels,  233. 

Spots,  291. 

Taking,  232. 
Colocynth,  340. 


Colon,  ascending,  228. 

Descending,  228. 

Transverse,  228. 
Color  blindness,  311. 

Of  the  blood,  131. 

Sensations,  311. 
Colorado,  161. 
Combustion,  135. 
Common  sensations,  284. 
Complementary  foods,  173. 
Composition  of  air,  122. 

Of  beefsteak,  220. 

Of  blood,  384. 

Of  bone,  354. 

Of  bread,  226. 

Of  butter,  226. 

Of  foods,  384. 

Of  gastric  juice,  385. 

Of  lymph,  101. 

Of  milk,  226. 

Of  potatoes,  226. 

Of  sweat,  156. 

Of  urine,  162. 
Compound  glands,  224. 
Conduction  of  heat  from  skin,  158. 
Cone,  urinary,  164. 
Cones  and  rods  of  eye,  305,  306. 
Conium,  340. 
Conjunctiva,  301. 
Consciousness,  261. 
Conservation  of  energy,  252. 
Constipation,  228. 
Constipating  foods,  229. 
Constrictors,  92. 
Consumption,  145,  146. 

Prevention  of,  148. 
Contagious  diseases,  145. 

Of  the  eye,  315. 
Contraction  of  auricle,  72,  73 

Of  ventricle,  72,  73. 
Control  of  respiration,  122. 
Convalescence  and  eyes,  314. 
Convection,  140. 

Of  heat  from  skin,  158. 


INDEX. 


407 


Convolutions  of  the  brain,  257. 

Of  cerebrum,  33. 

Cookery,  Chemistry  of, Williams, 372. 
Cooking,  192. 
Coordination,  263. 
Copper,  339. 

Sulphate,  206. 
Copperas,  339. 
Cord,  spinal,  88. 
Cords,  vocal,  322,  324,  325. 
Corn,  230. 
Cornea,  301. 

Corner  stone  of  physical  science,  252. 
Coronary  artery,  61. 

Vein,  60. 

Corpus  arantii,  62. 
Corpuscles  of  blood,  51,  95. 

Colorless,  work  of,  148. 

Red,  work  of,  128. 

Of  touch,  286. 
Correlation  of  energy,  252. 
Corrosive  sublimate,  339. 
Cortex,  cerebral,  261. 
Cotton  in  the  ears,  318. 
Coughing,  116. 
Cracked  wheat,  229. 
Cramps,  42. 

Cranial  nerves,  254,  260. 
Cricoid  cartilage,  322. 
Crico-arytenoid  muscle,  lateral,  323. 

Posterior,  322. 
Crossing  of  fibers  of  optic  nerves, 

311. 

Crothers,  on  alcohol,  275. 
Croton  oil,  340. 
Crown  of  tooth,  199. 
Crying,  116. 
Crystalline  lens,  303. 
Cultivation  of  the  voice,  327. 
Current,  induction,  272. 

Interrupted,  272. 
Custards,  229. 
Cutaneous  sensations,  285. 
Cutter,  on  alcohol,  94. 


Daily  excretions,  381. 

Expenditure  of  the  body,  387. 

Income  of  the  body,  387. 

Ration  of  a  United  States  sol- 
dier, 383. 
Dancing,  239. 
Dandruff,  152. 
Dead  dust,  143. 

Death  from  breaking  neck,  122. 
Decay  of  teeth,  202. 
Deep  breathing,  121. 
Dejecta,  172. 
Dental  formula,  200. 
Dentine,  200. 
Dentist,  202. 
Dermis,  151. 
Descending  colon,  228. 
Dessert,  231. 
Deterioration,  moral,  from  alcohol, 

Martin,  277. 
Dextrose,  219. 
Diabetes,  245. 
Dialysis,  221. 
Diaphragm,  108,  196. 

Ventral  view,  106. 
Diarrhea  from  cold,  232. 

Effect  on  strength,  232,  385. 

Effect  on  urine,  166. 
Diet  in  cold  climates,  174. 

Necessity  of  mixed,  173. 
Diffusion,  139. 

Of  liquids,  221. 
Digastric  muscles,  203. 
Digestion,  hygiene  of,  230. 

Organs  of,  198. 

Outline  of,  227. 

Time  of,  215,  386. 
Digestive  liquids,  amount  of,  385. 

Tube,  as  a  whole,  224. 
Digitalis,  340. 
Dinner,  a  good,  231. 
Dioxid,  carbon,  125. 
Diphtheria,  145. 
Direct  heating,  141. 


408 


INDEX. 


Disease  of  the  eyes,  contagious,  315. 

Germs,  145. 
Diseases,  contagious,  145. 

Of  Inebriety,  275. 
Disinfectants,  377. 
Disinfection,  377. 
Dislocation,  355. 
Dissection  of  brain,  253. 

Of  circulatory  system,  69. 

Of  digestive  system,  195. 

Of  eye,  302. 

Of  frog,  37. 

Of  head  of  rabbit,  202. 

Of  heart,  55. 

Of  kidney,  162. 

Of  larynx,  321. 

Of  lungs,  59. 

Of  muscle,  12, 13. 

Of  nervous  system,  29. 
Distinct  vision,  center  of,  306. 
Distribution  of  arteries,  69,  71. 

Of  veins,  69,  71. 
Dodging,  42. 
Dog,  bite  of,  337. 

Brainless,  260. 
Donoghue,  on  pie,  231. 
Dreams,  271. 
Dried  fruits,  361. 

Meats,  229. 
Drinks,  hot,  232. 
Drinking  cold  water,  173. 

Water,  172. 

Drinks,  temperance,  179. 
Dropsy,  102. 

Drowning,  resuscitation  from,  331. 
Drum-skin,  317. 
Duct,  bile,  196. 

Of  lachrymal  gland,  307. 

Lymph,  98. 

Pancreatic,  196. 

Of  salivary  glands,  203,  204. 

Of  sweat  gland,  154,  155. 

Thoracic,  98,  222. 
Ducts,  of  glands,  224. 


Dulcamara,  341. 

Duodenum,  196. 

Dura  mater,  33,  253. 

Duration  of  impressions  of  light,  312. 

Dust,  dead,  143. 

Of  house,  147. 

Live,  144. 

Sources,  143,  144. 

Ear,  bones  of,  317. 

Care  of,  318. 

External,  316. 

Internal,  316. 

Middle,  316. 
Economy  in  buying  meats,  370. 

Household,  scope  of,  3G4. 
Eddy,  a  living,  245. 
Efferent  root  of  spinal  nerve,  40. 
Eggs,  169,  370. 

Electric  light  for  reading,  313. 
Electrical  stimuli,  267. 
Electricity  and  nerve  impulse,  44. 
Elements  of  the  body,  383. 
Emetics,  336. 
Emulsion,  208,  219. 
Enamel,  200. 
Endothelium,  77,  78. 
Energy,  conservation  of,  252. 

Correlation  of,  252. 

Dormant  in  muscle,  136. 

Liberation  of,  251. 

Loss  of,  251. 

Potential,  115. 

Solar,  251. 

Source  of,  248. 

And  starvation,  251. 

Storing  of,  251. 

English  women  as  walkers,  237. 
Enlargement,  cervical,  32. 

Lumbar,  32. 
Entire  wheat,  229. 

Flour,  170. 
Enzymes,  206. 
Epidermis,  151. 


INDEX. 


409 


Epidermis,  structure  of,  153. 
Epiglottis,  210,  321. 
Epithelial  cells,  6. 
Equilibrium  sense,  317. 
Ergot,  341. 
Erysipelas,  145. 
Esophagus,  55,  196. 
Ether,  inhalation  of,  341. 
Eustachian  tube,  210,  317. 
Evaporation,  cooling  effect  of,  158. 
Excretion,  daily,  381. 

Need  of,  150. 
Exercise,  4,  234. 

Bodily,  Lagrange,  239. 

Effect  of,  159. 

Forms  of,  236. 

Physiology  of,  Lagrange,  28. 
Expectoration,  146. 
Expenditure  of  the  body  daily,  387. 
Experiment,  Aristotle's,  273. 
Experiments  with  pulse,  81. 

Illustrating  movements  of  res- 
piration, 109. 

Illustrating  chemistry  of  respi- 
ration, 123. 
Expiration,  114,  116. 
Extensor  muscle,  10,  12. 
External  ear,  316. 

Parts  of  the  eye,  301 
Extract  of  beef,  175. 
Eye,  dissection  of,  302. 

External  parts  of,  301. 

Protection  of,  307. 

Regulation  of  amount  of  light 

admitted,  311. 
Eyes,  care  of,  312. 

Contagious  disease  of,  315. 

During  convalescence,  314. 
Eyeball,  muscles  of ,  301. 
Eyelids,  307. 

Facets,  350. 

Facial  nerves,  255,  259. 

Fainting,  265,  330. 


Fare,  bills  of,  367,  375,  376. 
Farina,  230. 
Fasting,  Tanner,  381. 
Fat  and  starvation,  247. 

As  storage  tissue,  246. 

Weight  of,  in  body,  386. 
Fats,  as  food,  169. 

Importance  of,  357. 

Kinds  of,  357. 

Melting  points  of,  357. 
Fatigue,  264,  265. 
Fehling,  test  tablets,  206. 
Femoral  artery,  bleeding  from,  328. 
Fermentation  of  cider,  145. 
Ferment,  salivary,  205. 
Ferments,  unorganized,  206. 
Fever,  during  a  cold,  232. 

Scarlet  (see  Scarlatina). 

Typhoid,  145,  172. 

Yellow,  145. 

Fiber,  plain  muscle,  76,  77. 
Fibers,  association,  269,  270. 

Of  optic  nerve,  crossing,  311. 
Fibrin,  97,  168. 
Filiform  papillae,  297. 
Filtration,  221. 
Fire,  of  clothing,  330. 
Fireplaces,  139. 
Fish,  169. 

Poisonous,  340. 

Salted,  229. 
Fishing,  237. 
Fissure,  central,  262. 

Of  Silvius,  262. 
Flavors,  298,  362. 
Flexor,  10,  12. 
Flexure,  sigmoid,  228. 
Flour,  entire  wheat,  170. 

Graham,  229. 

White,  170. 

Fluids  of  the  body,  385. 
Food,  167. 

Preservation  of,  149. 
Foods,  accessory,  167. 


410 


INDEX. 


Foods,  carbohydrate-containing,  170. 

Complementary,  173. 

Composition  of,  384. 

Constipating,  229. 

Time  of  digestion,  386. 

Fatty,  174. 

Laxative,  229. 

Proteid-containing,  168. 
Foodstuffs,  167. 
Football,  237. 

Force,  indestructibility  of,  251. 
Forces  of  inspiration,  115. 
Formalin,  253. 
Formol,  253. 
Forms  of  exercise,  236. 
Formula,  dental,  200. 
Foster,  on  alcohol,  93. 
Foul-air  shaft,  141. 
Fowler's  Solution,  339. 
Foxglove,  340. 
Freckles,  152. 
Frog,  brainless,  259. 

Heart,  72. 

How  to  kill,  13. 

Web  of,  circulation  in,  52,  53. 
Fruit,  best  time  for,  232. 
Fruits,  361. 

Dried,  229. 
Frying,  193. 

Function,  definition  of,  5. 
Functions  of  cerebellum,  263. 

Of  cerebrum,  259. 

Of  nerve  roots,  40. 

Of  skin,  157. 
Fungiform  papillae,  297. 
Furnaces,  140. 

Game,  wild,  230. 
Ganglia,  36. 

Of  the  brain,  258. 

Sympathetic,  88,  89,  91. 
Ganglion,  32. 
Gargling,  117. 
Gases  of  the  blood,  130. 


Gases,  poisonous,  341. 
Gastric  glands,  213. 

Juice,  213. 

Juice,  action  of,  207. 

Juice,  composition  of,  385. 
Gaule,  on  alcohol,  182. 
Gelatin,  168. 
General  sensations,  267. 
Germs,  disease,  145. 

Yeast,  145. 
Gland,  essential  features  of,  155. 

Lachrymal,  307. 

Oil,  151. 

Parotid,  salivary,  202. 

Salivary,  diagram  of,  203. 

Sub-lingual,  salivary,  204. 

Sub-maxillary,  salivary,  203. 

Sweat,  151. 
Glands,  compound,  224. 

Evolution  of,  155. 

Excretory,  156. 

Gastric,  213. 

Intestinal,  216. 

Lymphatic,  57,  99,  222. 

Oil,  156. 

Salivary,  action  of,  204. 

Simple,  156,  224. 

Sweat,  154. 

Sweat,  number  of,  381. 
Glossary,  389. 

Glosso-pharyngeal  nerve,  255,  259. 
Gluten,  168. 

Glycerine  extract  of  pancreas,  208. 
Glycogen,  218,  247. 
Graham  flour,  229. 
Grains,  the,  170. 
Granula,  229. 
Grape  sugar,  206,  219. 
Grates  as  ventilators,  138. 
Gray  matter,  activity  of,  266. 

Matter  of  spinal  cord,  34. 

Nerve  fibers,  34. 
Greely,  on  alcohol,  184. 
Green  peas,  230. 


INDEX. 


411 


Growth  of  hair,  154. 

Of  nail,  154. 
Gullet,  55,  196,  321. 
Gum  chewing,  205. 
Gustatory  nerve,  258,  298. 

Habits,  281. 
Hair,  151. 

Growth  of,  154. 

On  head,  number,  381. 
Halliburton,  on  alcohol,  189. 
Hallucinations,  270. 
Hammer,  317. 
Hard  water,  171. 

Palate,  210. 

Harmony  in  muscle  action,  45. 
Hashish,  270,  280. 
Hauser,  Kaspar,  284. 
Haversian  canals,  352. 
Hawking,  117. 
Head,  number  of  hairs,  381. 

Of  rabbit,  dissection,  202. 
Hearing,  center,  2G2. 

Sense  of,  316. 
Heart,  action  of,  62,  72. 

And  lungs,  55. 

Apex  of,  75. 

Beat,  rate  of,  49,  72,  75. 

Dissection  of,  59. 

Frog's,  72. 

Muscle,  90. 

Nourishment  of,  86. 

Palpitation  of,  175. 

Sounds  of,  75. 

Structure  of,  59. 

Valves  of,  60,  61,  62,  74 

Weight  of,  386. 

Work  and  rest  of,  75. 
Heat,  distribution  of,  159. 

Production  of,  132. 

Production,  regulation  of,  159. 

Radiant,  140. 

Regulation  by  skin,  157. 

Restoration  of,  333. 


Heat  saver,  the,  367. 
Heating,  direct,  141. 

Indirect,  141. 

And  ventilation,  137. 
Hellebore,  341. 
Helmholtz,  on  alcchol,  182. 
Hemiglobin,  96,  128. 
Hemiplegia,  261. 
Hemispheres  of  cerebrum,  33,  254, 

261. 

Hemlock,  340. 
Hemorrhage,  how  to  stop,  328. 

Of  lungs,  329. 

Of  stomach,  329. 
Hepatic  artery,  217. 

Vein,  70. 

Herbivora,  174,  216. 
Hibernating  animals,  247. 
Hiccuping,  117. 
Hilum,  161,  162. 
Hodge,  on  alcohol,  182. 
Hopping,  236. 
Horn,    ventral,   of    gray   matter  of 

spinal  cord,  35. 

Horseback  riding,  236,  237,  238. 
Hot  bread,  229. 
Hot  drink,  232. 
House  dust,  147. 
Howell  on  absorption,  221. 
Humor,  aqueous,  303. 

Vitreous,  304. 
Hunger,  267,  296. 
Huxley,  living  eddy,  245. 
Hydrochloric  acid,  207. 
Hydrogen,  169. 

Sulphuretted,  341. 
Hygiene  of  bones,  355. 

Of  breathing,  120. 

Definition  of,  5. 

Of  digestion,  230. 

Of  joints,  355. 
Hyoid  bone,  322. 
Hyoscyamus,  278,  341. 
Hypoglossal  nerve,  256. 


412 


INDEX. 


Ice,  artificial,  172. 

Impurities  of,  172. 

Water,  172,  173. 
Iliac  arteries,  70. 

Veins,  70. 

Illusions  of  touch,  290. 
Image  inverted  on  retina,  308. 
Imagination,  273. 
Importance  of  fats,  357. 
Impressions   of    light,   duration  of, 

312. 

Impurities  in  water,  171. 
Incisor  teeth,  199,  200. 
Income  of  body,  daily,  387. 
Indestructibility  of  force,  251. 

Of  matter,  250. 
Indirect  heating,  141. 
Induction  current,  272. 
Inebriety,  Clum,  275. 

Diseases  of,  Crothers,  275. 
Inferior  oblique  muscle,  301. 
Inhibition,  44,  92. 

In  fainting,  265. 

Reflex,  92. 
Injecting  apparatus,  68. 

Arteries,  65. 
Injection  mass,  66. 

Of  thoracic  duct,  223. 
Innominate  vein,  70 
Inorganic  world,  248. 
Insertion  of  muscle,  12,  15. 
Inspiration,  113,  115. 
Intelligence,  260. 
Intensity  of  stimulus,  268. 
Internal  ear,  316. 

Respiration,  136. 
Interrupted  current,  272. 
Intervertebral  cartilages,  350. 
Intestinal  glands,  216. 

Juice,  216,  219. 
Intestine,  195,  216. 

Large,  196. 

Small,  196,  216. 
Inventors,  264. 


Inverted  image  on  retina,  308. 
Invertin,  21!). 
Iodine,  339. 
Iris,  303. 

Action  of,  311. 
Iron,  173,  339. 

Oxid,  125. 

Sulfate,  172. 
Irritants,  animal,  340. 

Metallic,  339. 

Vegetable,  340. 

Joints,  classification  of,  354. 

Dissection  of,  24. 

Hygiene  of,  355. 

Stiffened,  355. 
Judgment,  273. 
Jugular  vein,  70. 

Valves  in,  82. 
Juice,  gastric,  213. 

Gastric,  composition  of,  385. 

Intestinal,  216. 

Pancreatic,  217. 
Jumping,  236. 

Kaspar  Hauser,  284. 
Katabolic  stair,  248. 
Katabolism,  250. 
Kidney,  the,  161. 

Diseased,  245. 

Dissection  of,  162. 

Microscopic  structure  of,  163. 
Killing  a  frog,  13. 

A  cat,  67. 

Kingsley,  The  Two  Breaths,  l.'iG. 
Knot,  surgeon's,  67. 

La l)ii i-ii ii in ,  341. 
Lachrymal  gland,  307. 
Lacteals,  220,  222. 
Lacunae,  353. 

Lagrange,  Physiology  of  Bodily  Ex- 
ercise, 28,  239. 
Lamellse,  353. 


INDEX. 


413 


Large  intestine,  196,  228. 
Larynx,  55,  321. 

Dissection  of,  321. 

Of  calf,  321. 

Lateral  crico-arytenoid  muscle,  323. 
Laughing,  116. 
Laxative  foods,  229. 
Lead,  339. 

Ledger  account  of  body,  241. 
Legumin,  168. 
Lens  capsule,  304. 

Crystalline,  303. 
Lemons,  229. 
Levers,  21. 

Liberation  of  energy,  251. 
Ligaments,,  24. 
Light  admitted  to  eye,  regulation  of, 

311. 

Lime,  173,  338. 

Liquids  of  body,  specific  gravity  of, 
385. 

Digestive,  amount  of,  385. 
Live  dust,  144. 
Liver,  195,  217,  218. 

As  food,  230. 

Weight  of,  386. 
Living  machines,  251. 
Lobelia,  341. 
Lobes,  olfactory,  33,  254. 
Local  sign,  289. 

Localization  of  touch  sensations,  288. 
Location  of  brain  functions,  261,  262. 
Lock-jaw,  42. 
Locomotion,  25. 
Locomotive  and  body,  134,  135. 
Longevity  and  alcohol,  Baer,  188. 
Loss  of  energy,  251. 

Of  water  from  the  body,  383. 
Loudness  of  voice,  325. 
Lumbar  vertebra,  350,  351. 
Lung,  apex  of,  108. 

Base  of,  108. 

Bleeding  from,  329. 

Capacity,  117. 


Lung  diseases,  death  from,  148. 

Dissection  of,  55,  59. 
Lungs  and  heart,  55. 
Lymph,  the,  98,  246. 

Capillaries,  98. 

Cavities,  98. 

Composition  of,  101. 

Duct,  98. 

Around  glands,  155. 

Spaces,  98. 

Veins,  98,  222. 
Lymphatics,  222. 
Lymphatic  glands,  57,  99,  222. 

Machines,  living,  251. 

Magnesium  oxid,  125. 

Malted  milk,  175. 

Marrow  cavity,  24. 

Martin,  on  alcohol,  277. 

Massage,  103. 

Masseter  muscle,  11,  203. 

Master  tissue,  252. 

Mastication,  effects  of  incomplete, 

209. 
Mater,  dura,  253. 

Pia,  253. 

Matter,  indestructibility  of,  250. 
M'Kendrick,  on  alcohol,  190. 
Meal,  foodstuffs  in,  226. 
Measles,  145. 

Measurement  of  tissues,  387. 
Meat,  168. 

Boiling,  193. 

Dried,  229. 

Economy  in,  370. 

Smoked,  229. 
Meatus,  auditory,  317. 
Mechanical  respiration,  136. 

Stimuli,  266. 
Mediastinal  space,  108. 
Medulla  oblongata  (see  Spinal  Bulb). 
Medullary  cavity,  23. 
Membrane,  mucous,  107,  205,  321. 

Tympanic,  317. 


414 


INDEX. 


Memory,  273. 
Meningitis,  266. 
Mercury,  339. 
Mesentery,  196,  197. 
Mesenteric  artery,  70. 

Vein,  70. 
Metabolism,  250. 
Metallic  irritants,  339. 
Microscopic  structure  of  bone,  352. 
Middle  ear,  316. 
Middlings,  170. 
Milk,  167,  169,  370. 

Bacteria  in,  149. 

Boiled,  230. 

Composition  of,  226. 

Heating,  173. 

Malted,  175. 

Peptonized,  175. 

Teeth,  201. 

Mitchell,  Wear  and  Tear,  283. 
Mixed  diet,  necessity  of,  173. 
Molar  teeth,  200. 
Molasses,  New  Orleans,  229. 
Mold,  145. 

Moral  deterioration  by  alcohol,  Mar- 
tin, 277. 
Morphine,  341. 
Motion,  9. 

Production  of,  132. 

And  sensation,  29. 
Motor  centers,  261,  262. 
Mountain  climbing,  amount  of  urea, 
248. 

Effect  of  alcohol  on,  181. 
Mouth,  the,  198. 

Breathing  through,  142. 
Movements  of  respiration,  113. 
Mucous  glands,  205,  212. 

Membrane,  205,  321. 
Mucus,  107,  205,  212. 
Muriatic  acid,  338. 
Muscle,  action  df,  13. 

Action  of,  laws  of,  17. 

Arytenoid,  323. 


Muscle,  calf  of  frog,  13. 

Ciliary,  307,  309. 

Digastric,  203. 

Fiber,  non-striated,  77. 

Fiber,  plain,  76,  77. 

Of  heart,  90. 

Inferior  oblique,  301. 

Lateral  crico-arytenoid,  323. 

Masseter,  203. 

And  nerve,  12. 

Nerve  preparation,  13. 

Posterior  crico-arytenoid,  322. 

Sheath,  15. 

Striated,  15. 

Striped,  15. 

Structure  of,  11. 

Superior  oblique,  301. 

Temporal,  204. 

Thyro-arytenoid,  323. 
Muscles,  abdominal,  195. 

And  bones,  20. 

Engines  of  motion,  248. 

Experiments  with,  10. 

Of  eyeball,  301. 

And  Nerves,  Rosenthal,  47. 

Papillary,  61. 

Recti,  of  the  eye,  301. 

Of  respiration,  113,  122. 

Sphincter,  215. 

Of  stomach,  213. 

Symmetrical  development  of,  18 

Weight  of,  386. 
Muscular  contraction,  17 

Sense,  292. 
Mustard,  336. 
Mutton,  168,  358,  384. 
Myosin,  168. 

Nails,  growth  of,  154. 
Narcotics,  278,  340. 
Nasal  passage,  210. 
Nature  of  sensation,  269. 

Of  sensation,  relative,  272. 
Nausea,  284,  294. 


INDEX. 


415 


Necessity  of  mixed  diet,  173. 
Neck  of  tooth,  199. 
Negative  after-image,  312. 
Nerve  cells,  35,  36. 

Centers,  36,  43,  87,  93,  122,  155, 
263,  270. 

Centers,  of  glands,  155. 

Chain,  90,  91. 

Current,  38. 

Endings  in  the  skin,  285. 

Fiber,  33. 

Fiber  sheath,  34. 

Fibers,  vaso-constrictors,  92. 

Fibers,  vaso-dilators,  92. 

Glosso-pharyngeal,  255,  259. 

Impulse,  34,  38. 

Optic,  301,  302. 

Pneumogastric,  256,  259. 

Sciatic,  37. 

Stimuli,  266. 

Trunk,  40. 
Nerves,  auditory,  255,  259. 

Cranial,  254,  260. 

Facial,  255,  259. 

Gustatory,  258,  298. 

Hypoglossal,  256. 

Olfactory,  258,  299. 

Optic,  254,  258,  260,  302. 

Pneumogastric,  91,  92,  256,  259. 

Spinal,  32. 

Structure  of,  33. 

Of  sweat  gland,  155. 

Sympathetic,  88,  89. 

Vaso-motor,  93. 
Neural  arch,  346,  348. 

Ring,  346,  348. 
Neuralgia  of  face,  254. 
Neuroglia,  258. 
Newspaper  reading,  314. 
Nightshade,  340. 
Nitrate  of  silver,  340. 
Nitric  acid,  338. 
Nitrogen  of  air,  122. 

Preparation  of,  123. 


Nitrogen,  properties  of,  124. 
Nitrous  oxid,  341. 
Nose,  bleeding  from,  329. 
Nourishment  of  walls  of  heart,  86. 
Number  of  hairs  on  head,  381. 

Of  sweat  glands,  381. 
Nurse,  the,  343. 
Nutrition,  248. 

Science  of,  365,  374. 
Nuts,  231. 
Nux  vomica,  341. 

Oatmeal,  229. 

In  drinking-water,  173. 
Oblique  muscle,  inferior,  301. 

Superior,  301. 
Odontoid  process,  350. 
Odors,  pungent,  300. 
Oil,  croton,  340. 

Glands,  151,  156. 

Savin,  340. 
Olfactory  lobes,  33,  254. 

Nerves,  258,  299. 
Onion,  230,  363. 
Opium,  279,  341. 
Optic  nerve,  254,  258,  301,  302. 

Crossing  of  fibers,  311. 
Oranges,  229. 
Organ,  definition  of,  5. 
Organs  of  abdomen,  195. 

Of  digestion,  198. 
Origin  of  muscle,  12. 
Osmosis,  221. 
Outline  of  digestion,  227. 
Oven,  the  Aladdin,  371,  374. 
Oxalic  acid,  338. 
Oxid,  carbonic,  341. 

Iron,  125. 

Magnesium,  125. 

Nitrous,  341. 

Phosphoric,  123. 
Oxidation  of  metals,  125. 

In  the  tissues,  132,  134. 
Oxygen  in  the  air,  122. 


416 


INDEX. 


Oxygen,  properties  of,  124. 
Oxy-hemoglobin,  128. 
Oysters,  230. 

Pain,  285,  294. 
Palate,  hard,  210. 

Soft,  210. 
Palpitation,  175. 
Pancreas,  196,  217. 
Pancreatic  duct,  196. 

Juice,  217. 

Juice,  action  of,  207. 
Pancreatin,  207. 
Papillae  of  skin,  151,  153. 

Of  tongue,  297. 

Circumvallate,  297. 

Filiform,  297. 

Fungiform,  297. 
Paralysis,  261. 
Paris  Green,  339. 
Parotid  salivary  gland,  202. 
Parts  of  the  body,  weight  of,  386. 
Pastry,  229,  232. 
Peaches,  229. 
Peas,  169,  230. 
Pepsin,  213. 

Amount  of,  213. 

Test,  207. 
Peptone,  214. 
Peptonized  milk,  175. 
Pericardial  fluid,  57. 
Pericardium,  57. 
Periosteum,  25. 
Peristaltic  motion,  195. 
Peritoneal  cavity,  102. 
Peritoneum,  195,  197. 
Perspiration,  amount  of,  157. 

Insensible,  156. 

Sensible,  157. 

Variation  of,  157. 
^harynx,  210. 
Phosphate  of  calcium,  173. 
Phosphates  in  flour,  170. 
Fhosphorus,  340,  123. 


Phosphoric  oxid,  123. 

Physical  science,  cornerstone  of,  252. 

Physiological  division  of  labor,  6. 

Physiology,  definition  of,  5. 

Physostigma,  341. 

Pia  mater,  253. 

Pickpockets,  272. 

Pie,  231. 

Pigeon,  brainless,  259. 

Pigment  cells,  52. 

Pigment  layer  of  eye,  305,  307. 

Of  skin,  152. 

PikeVPeak,  climbing,  181. 
Piles,  228. 
Pitch  of  voice,  325. 
Plain  muscle  fiber,  76,  77. 
Plan  of  absorption,  220. 

Of  circulation,  85,  131,  242,  243, 

244. 

Plasma,  52,  95,  97. 
Pleura,  56,  108. 
Pleurisy,  108,  295. 
Plexus,  91. 

Brachial,  32. 

Solar,  90,  91. 
Plums,  229. 

Pneumogastric  nerves,  91,  25(5,  259. 
Poison  ivy,  342. 

Poisons  and  antidotes,  336,  338-341. 
Poisoning  in  food,  149. 
Poisonous  fish,  JM). 
Pollen,  144. 
Pores,  sweat,  151,  154. 
Pork,  168,  359,  370. 
Portal  circulation,  217. 

Vein,  70. 

Positive  after-image,  312. 
Postcaval  vein,  70,  217. 
Posterior     crico-arytenoid     muscle, 

322. 
Potash,  338 

Caustic,  206. 
Potatoes,  230,  361. 

Composition  of,  226. 


INDEX. 


417 


Potential  energy,  115. 

Poultry,  229. 

Power  through  Eepose,  Call,  281. 

Precaval  vein,  70. 

Premolar  teeth,  200. 

Preservation  of  brain,  253,  387. 

Of  food,  149. 
Pressure  sense,  285,  287. 

On  veins,  effect  of,  83. 
Privies,  171. 

Process,    anterior  articulating,   348, 
349. 

Ciliary,  304. 

Odontoid,  350. 

Posterior  articulating,  348,  349. 

Spinous,  348. 

Transverse,  348. 

Of  vertebra,  340,  348,  349. 
Production  of  heat,  132. 

Regulation  of,  159. 
Pronation,  352. 
Protection  of  eye,  307. 
Proteid,  circulating,  249. 
Proteid-containing  foods,  108. 
Proteids,  108. 

Artificial  digestion  of,  207,  208. 

Characteristics,  108. 

Vegetable,  109. 
Protoplasm,  0,  249. 

Animal  and  vegetable,  248. 
Prunes,  229. 
Prussic  acid,  338. 
Ptyalin,  205. 

Pulmonary  capillaries,  112. 
Pulp  cavity  of  tooth,  199,  200. 
Pulse,  49,  81. 

Experiments  with,  81. 
Pungent  odors,  300. 
Pupil  of  eye,  303. 
Pylorus,  215. 
Pyramid,  urinary,  103. 

Quality  of  voice,  326. 
Quantity  of  water  in  organs,  383. 


Rabbit,  brain  and  spinal  cord  of,  29, 
253. 

Dissection  of  head,  202. 

Sympathetic  nerve  of,  80,  92. 
Racing,  230. 

Radiation  of  heat  from  skin,  158. 
Rain,  effect  on  air,  143. 

Water,  170. 
Raspberries,  230. 
Rate  of  blood-flow,  84. 

Of  circulation,  381. 

Of  heart-beat,  49,  72. 
Ration,  daily,  of  U.  S.  soldier,  383. 
Reaction  in  locomotion,  20. 

In  expiration,  110. 

Time,  208. 
Reading,  313. 

Receptacle  of  chyle,  98,  223. 
Recreation,  204. 
Rectum,  197,  228. 
Rectus  muscle,  301. 
Reflex  action,  30,  38,  208,  209. 

Action,  essentials  of,  41. 

Action,  importance  of,  42 

Action  of  spinal  cord  of  frog,  30. 

Action,  process  of,  42. 
Reflex  arc,  38. 

Regulation  of  amount  of  light  to  eye, 
311. 

Of  blood-supply,  76,  77,  87. 

Of  heat  by  skin,  157.f 

Of  heat  production,  159. 
Reid,  bear  story,  247. 
Relative  nature  of  sensations,  272. 
Renal  artery,  70,  162. 

Vein,  70,  162. 
Rennet,  214. 
Rennin,  214. 

Repose,  Power  through,  Call,  47,  281 
Respiration,  105. 

Abdominal,  110. 

Control  of,  122. , 

Costal,  110. 

Effect  on  circulation,  121. 


418 


INDEX. 


Respiration,  effect  on  movement  of 
lymph,  121. 

Chemistry  of,  123. 

Diaphragmatic,  116. 

Experiments  illustrating,  109. 

Hygiene  of,  120. 

Internal,  136. 

Mechanical,  136. 

Movements  of,  113. 

Muscles  of,  113,  122. 

Rate,  how  affected,  116. 

Thoracic,  116. 

Time  of,  116. 

And  work,  133. 
Respiratory  center,  122. 

Sounds,  121. 
Rest  and  work  of  heart,  75. 

Technique  of,  Brackett,  47,  281. 
Resting,  281. 

The  eyes,  314. 
Restoration  from  fainting,  265,  330. 

Of  animal  heat,  333. 
Resuscitation  from  drowning,  331. 
Retina,  305,  306. 

Inverted  image  on,  308. 
Rhubarb,  230. 

Rhythmic  action  of  heart,  90. 
Rice,  230. 
Ring,  neural,  346. 
Rods  and  cones  of  eye,  306. 
Rohe,  on  alcohol,  186. 
Root  beer,  179. 
Root  of  tooth,  199. 

Of  lung,  108. 
Roots,  of  nerves,  dorsal,  32. 

Of  nerves,  ventral,  32. 
Rope-skipping,  236. 
Rosen  thai,  Muscles  and  Nerves,  47. 
Round  steak,  169. 
Rugby,  School  Days  at,  239. 
Rugs,  advantages  of,  147. 
Rum  ford,  soup  kitchens,  365. 
Running,  26. 
Rusty  nails,  wounds  from,  337. 


Sac,  bile,  19(5. 

Sacrum,  350. 

Sago,  230. 

Saline  solution,  normal,  14. 

Salines,  298. 

Saliva,  action  of,  205. 

Amount  of,  205. 

Tests  of,  206. 
Salivary  ferment,  205. 

Gland,  diagram  of,  203. 

Gland,  parotid,  202,  204. 

Gland,  sublingual,  204. 

Gland,  submaxillary,  203,  204 
Salts,  173. 
Satiety,  284. 
Savin  oil,  340. 
Scarlatina,  145. 
Scarlet  fever  (see  Scarlatina). 
Scheele's  Green,  339. 
School  Days  at  Rugby,  239. 
Sciatic  nerve,  12,  13,  32. 
Sclerotic  coat,  304. 
Seasonings,  362. 
Sedgwick  and  Wilson,  246. 
Semicircular  canals,  318. 
Sensation,  270. 

Centers,  262. 

Of  color,  311. 

And  motion,  29. 

Nature  of,  269. 
Sensations,  common,  284. 

Cutaneous,  285. 

General,  267. 

Relative  nature  of,  272. 

Of  touch,  localization  of,  288. 
Sense  of  equilibrium,  317. 

Of  hearing,  316. 

Muscular,  292. 

Of  pressure,  285,  287. 

Of  position,  292. 

Of  sight,  300. 

Of  smell,  298. 

Of  taste,  296. 

Of  temperature,  290. 


INDEX. 


419 


Senses,  special,  284. 

Sensory  root  of  spinal  nerve,  40. 

Serous  cavities,  102. 

Serum,  97. 

In  blister,  152. 
Sewall,  on  muscular  sense,  293. 

Sense  of  touch,  290. 
Sheath,  medullary,  34. 

Muscle,  15. 

Muscle  fiber,  16. 

Nerve  fiber,  34. 
Shooting,  237. 
Sick,  care  of,  342. 
Sick-room,  dust,  344. 
Sighing,  117. 
Sigmoid  flexure,  228. 
Sign,  local,  289. 
Silver,  nitrate  of,  340. 
Silvius,  fissure  of,  262. 
Simple  glands,  156,  224. 
Size  of  cells,  387. 
Skeleton,  346,  347,  380. 

Appendicular,  346. 

Axial,  346. 

Weight  of,  352,  386. 
Skin,  functions  of,  157. 

As  heat  regulator,  157. 

Nerve  endings  in,  285. 

Structure  of,  151. 

Thickness  of,  152. 

Weight  of,  152,  386. 
Skipping  the  rope,  236. 
Skull,  347,  352. 
Sleep,  263,  264. 

Loss  of,  264. 
Sleeplessness,  264. 
Sleight-of-hand  performer,  272. 
Small  intestine,  196,  216. 
Small-pox,  145. 
Smell,  brain  center  of,  262. 

Sense  of,  298. 
Smelling  salts,  265. 
Smith,  on  alcohol,  182. 
Smoked  meats,  229. 


Snake  bites,  337. 
Sneezing,  116. 

Prevention  of,  345? 
Snell,  mountain  climbing,  181. 
Sniffing,  117. 
Snoring,  117. 
Snowballing,  236. 
Snowstorm,  effect  on  air,  143. 
Soap,  233. 
Sobbing,  116. 
Soda,  330,  338. 
Sodium  bicarbonate,  208. 
Soft  palate,  210. 
Solar  energy,  251. 

Plexus,  90,  91. 
Soldier,  United  States,  daily  ration 

of,  383. 
Sound,  317. 

Bodies,  Blaikie,  28. 

Waves,  317. 
Sounds  of  heart,  75. 

Respiratory,  121. 
Soups,  first  course,  231. 
Soup-making,  193,  366. 
Special  senses,  284. 
Specific  gravity  of  liquids  of  body, 

385. 
Speech,  326. 

Center,  262,  270. 
Sphincter  muscles^  215. 
Spices,  363. 
Spinach,  230. 
Spinal  bulb,  33,  254,  263. 

Cord,  88. 

Cord  and  brain,  cat  or  rabbit,  29. 

Cord,  cross  section  of,  34. 

Cord,  functions  of,  43. 
Spinous  process,  348. 
Spitting  on  floors,  146. 
Spleen,  the,  102. 
Splenic  vein,  70. 
Spoiling  of  food,  149. 
Sponge  bath,  233. 
Spores,  144,  172. 


420 


I\I)EX. 


Spot,  blind,  310. 

Yellow,  306. 
Spots,  cold,  291. 

Warm,  291. 
Sprains,  355. 
Spring  water,  171. 
Squash,  230. 
Stair,  anabolic,  248. 

Katabolic,  248. 
Standing,  25. 
Stanley,  on  alcohol,  184. 
Starch,  170,  359. 

Excess  of,  360. 
Starvation  and  energy,  251. 

And  fat,  247. 

And  weight,  383. 
Steak,  round,  169. 

Tenderloin,  169. 
Steapsin,  219. 
Stereoscopic  vision,  312. 
Stevenson  and  Murphy,  on  alcohol, 

93,  274. 

Stiffened  joints,  355. 
Stimuli,  electrical,  267. 

Intensity  of,  268. 

Of  nerves,  266. 
Stirrup,  316,  317. 
Stockham,  Tokology,  229. 
Stomach,  195,  212,  213. 

Absorption  from,  215.  • 

Bleeding  from,  329. 

Digestion,  time  of,  215. 

Muscles  of,  213. 
Storing  energy,  251. 
Stove  and  body,  134. 
Stramonium,  278. 
Strong,  How  to  Get,  Blaikie,  235. 
Structure  of  abdomen,  197. 

Arteries,  78. 

Bone,  23,  24,  353.      ' 

Brain,  253,  255. 

Ear,  316. 

Eye,  302. 

Gland,  gastric,  214. 


Structure  of  gland,  salivary,  203. 

Heart,  59. 

Joints,  24. 

Kidney,  162. 

Larnyx,  321. 

Lung,  59, 105,  112. 

Muscle,  14. 

Nerve,  33. 

Nerve  fiber,  34. 

Retina,  306. 

Skin,  151,  152. 

Spinal  cord,  35. 

Stomach,  213. 

Thorax,  106,  108,  110,  114. 

Tooth,  199. 

Villus,  223,  224. 
Strychnine,  341. 
Subclavian  artery,  69. 

Vein,  70. 

Sublimate,  corrosive,  339. 
Sublingual  salivary  gland,  204. 
Subrnaxillary    salivary    gland,   203, 

204. 

Suffocation  in  wells,  335. 
Sugars,  170,  360. 
Sulphate  of  copper,  206. 

Of  iron,  172. 

Sulphuretted  hydrogen,  341. 
Sulphuric  acid,  338. 
Summer  complaint,  232. 
Sunlight,  161. 
Sunshine,  161. 
Sunstroke,  331. 
Superior  oblique  muscle,  301. 

Kectus  muscle,  301. 
Supination,  352. 
Swallowing,  210,  212. 
Sweat,  151,  156. 

Amount  of,  156. 

Cold,  156. 

Composition  of,  156. 

Gland,  151,  154. 

Glands,  number  of,  381. 

Pores,  154. 


INDEX. 


421 


Sweating,  effect  on  urine,  106. 
Sweeping,  147. 

In  the  sick-room,  344. 
Swimming,  335. 
Symmetry,  18,  19. 
Sympathetic  nerves,  34,  88,  89,  91. 
Synovia,  24. 
Syringe  in  heart  experiments,  65. 

In  pulse  experiment,  80. 

Table  of  the  bones,  380. 
Tag,  236. 

Taking  cold,  160,  232. 
Tanner,  fasting,  381. 
Taper,  wax,  125. 
Tapioca,  230. 
Tartar  emetic,  339. 
Tartaric  acid,  338. 
Taste  buds,  298. 

Sense  of,  296. 

Taylor,  Bayard,  hashish,  280. 
Tea,  173,  174,  230. 

Beef,  175. 

Tear,  Wear,  and,  Mitchell,  283. 
Tears,  307. 

Technique  of  Rest,  Brackett,  47,  281. 
Tetanus,  42. 
Teeth,  the,  199. 

Arrangement,  200. 

Care  of,  202. 

Decay  of,  202. 

Kinds,  200. 

Milk,  201. 

Nerves  of,  254. 

Time  of  appearance,  201. 
Temperance  drinks,  179.  " 
Temperature   affected   by  clothing, 
160. 

Affected  by  food,  160. 

Of  body,  157. 

Regulation  by  skin,  157. 

Of  the  sick-room,  343. 

Sense,  285,  290. 
Temporal  muscle,  11,  204. 


Tenderloin,  169. 

Tendon,  Achilles',  12 

Tennis,  237. 

Test  tablets,  Fehling's,  206. 

Thein,  174. 

Theobromin,  175. 

Thirst,  267,  296. 

Thompson,  on  alcohol,  182. 

Thorax,  cross  section  of.  110. 

Diagrams  of,  108,  114. 

Shape  of,  352. 

Ventral  view  of,  106. 
Thoracic  aorta,  69. 

Duct,  220,  222. 

Duct,  injection  of,  223. 

Vertebra,  348. 

Viscera,  weight  of,  386. 
Thyro-arytenoid  muscle,  323. 
Thyroid  cartilage,  '321. 
Time  of  gastric  digestion,  215,  386. 

Reaction,  268. 
Tin,  340. 

Tissue,  connective,  15,  16. 
Tissues,  definition  of,  5. 

Measurement  of,  387. 

Of  the  body,  386. 

Oxidation  in,  134. 
Toadstools,  341. 
Tobacco,  191,  341. 
Tokology,  Stockbam,  229. 
Tomatoes,  230. 
Tom  Brown,  239. 
Tongue,  the,  198,  297. 

Nerves  of,  297. 

Papillae  of,  297. 

Sensitiveness  of,  289. 
Tooth,  crown  of,  199. 

External  parts,  199. 

How  to  make  sections  of,  200. 

Neck  of,  199. 

Picks,  202. 

Powder,  202. 

Pulp  cavity  of,  199,  200. 

Root  of,  199. 


422 


INDEX. 


Tooth,  structure  of,  200. 
Touch  corpuscle,  286. 

Illusions  of,  290. 

Sense  of,  286. 

Touch-sensations,  localization  of  ,288. 
Touching  objects,  285. 
Trachea,  55,  105. 
Transfusion  of  blood,  103. 
Transverse  colon,  228. 

Process,  348. 
Triceps  muscle,  10. 
Trypsin,  218. 
Tube,  eustachian,  317. 
Tuberculosis,  145. 
Turbinated  bones,  299. 
Turpentine,  341. 
Typhoid-fever,  145,  172. 
Tympanic  membrane,  317. 
Tympanum,  membrane,  317. 

Underclothing,  changing,  161. 
Underwear,  161. 
Unorganized  ferments,  206. 
Unstriated  muscle  fibers,  76,  77. 
Upsetting  of  boats,  335. 
Urea,  161. 

Amount  of,  248. 
Ureter,  161. 
Urinary  capsule,  165. 

Cone,  164. 

Pyramid,  163. 
Urine,  161. 

Amount  of,  166. 

Composition  of,  162. 

Valve,  mitral,  61. 

Tricuspid,  60. 
Valves  of  heart,  60,  61. 

Of  heart,  action  of,  73,  74. 

Of  lacteals,  223,  224. 

Semilunar,  61. 

Of  thoracic  duct,  223. 

Of  veins,  50,  82,  83. 
Vaso-constrictor  nerves,  92. 


Vaso-dilator  nerves,  92. 
Vaso-motor  nerves,  93. 
Veal,  168. 
Vegetable  irritants,  340. 

Proteids,  1G(J. 
Vegetables,  371. 
Vegetarians,  174. 
Vein,  gastric,  70. 

Innominate,  70. 

Mesenteric,  70. 

Pancreatic,  70. 

Portal,  70. 

Postcaval,  57,  70. 

Precaval,  57,  70. 

Splenic,  70. 
Veins,  54,  82. 

Bleeding  from,  329. 

Cardiac,  60. 

Coronary,  60. 

Distribution  of,  69,  71. 

Effect  of  pressure  on,  83. 

Hepatic,  70. 

Iliac,  70. 

Jugular,  70. 

Lymph,  98,  222. 

Pulmonary,  58. 

Renal,  70,  162. 

Structure  of,  79. 

Subclavian,  70. 

Valves  of,  50,  82,  83. 
Ventilation,  137. 

Of  the  blood,  136. 
Ventricle,  57,  60. 

Contraction  of,  72. 

Of  brain,  254. 
Ventriloquist,  272. 
Verdigris,  339. 
Vermiform  appendix,  228. 
Vermilion,  339. 
Vertebrae,  346. 

Cervical,  349. 

Lumbar,  350,  351. 

Thoracic,  348. 
Vesicles  of  lung,  105, 112,  129. 


INDEX. 


423 


/i 


iili/197,  220,  223. 

Structure  of,  223,  224. 
Virchow,  on  alcohol,  94. 
Viscera,  abdominal,  weight  of,  386. 

Thoracic,  weight  of,  38G. 
Vision  center,  262. 

Stereoscopic,  312. 
Vital  capacity,  118,  119. 
Vitreous  humor,  304. 
Vitriol,  blue,  206,  339. 

White,  340. 

Vocal  cords,  322,  324,  325. 
Voice,  the,  320. 

Cultivation  of,  327. 

Loudness  of,  325. 

In  lower  animals,  326. 

Quality  of,  326. 

And  speech,  326,  327. 
Volition,  259,  261. 
Vomiting,  336. 

Walking,  25. 

As  exercise,  236,  237,  238,  265. 
Waller,  coasting  proteid,  249. 
Warm  baths,  prolonged,  234. 

Blooded  animals,  160. 

Spots,  291. 
Water,  170. 

Effect  of  boiling,  172. 

Hard,  171. 

Loss  of  from  body,  383. 

Rain,  170. 

In  tissues,  383. 
Waste  matter,  128,  149,  151,  161,  245. 

Organic,  127. 

Wear  and  Tear,  Mitchell,  283. 
Web,  frog's,  circulation  in,  53,  54. 
Weight  during  starvation,  383. 

Of  parts  of  body,  386. 


Wells  and  cesspools,  171. 

Suffocation  in,  335. 
Well-water,  171. 
Wheat,  170. 

Cracked,  229. 

Entire,  flour,  170. 
Whirlpool  and  living  being,  245. 
Whisky  for  snake-bites,  342. 
Whispering,  327. 

In  the  sick-room,  344. 
White  bread,  229. 

Flour,  170. 

Matter  of  spinal  cord,  34,  35. 

Vitriol,  340. 
Wild  game,  230. 
Wilderness  cure,  148. 
Will,  the,  253,  259. 

Power,  264. 

Williams,  Chemistry  of  Cookery,  372. 
Wilson  and  Sedgwick,  246. 
Wind,  139. 
Windpipe,  55. 
Winking,  42. 

Woodhull,  on  alcohol,  184. 
Woodruff,  on  alcohol,  185. 
Woollen  clothing,  160. 
Work  and  respiration,  133. 

And  rest  of  heart,  75. 
World,  inorganic,  248. 
Wounds,  bleeding  from,  328. 

From  rusty  nails,  337. 

From  thorns,  337. 

Yawning,  117. 
Yeast,  145. 
Yellow-fever,  145. 
Spot,  306. 

Zinc,  340. 


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NOM 


s 


BIOLOGY 

3 


UNIVERSITY  Q*  CALIFORNIA  lylBRARY 


